SCIENCE
CLASS FIVE
Department of Curriculum Research and Development
Ministry of Education
Royal Government of Bhutan
Published by
Department of Curriculum Research and Development (DCRD), Ministry of Education, Royal Government
of Bhutan
Provisional edition 2012
Copyright © Department of Curriculum Research and Development, Ministry of Education
Acknowledgment
The Department of Curriculum Research and Development, Ministry of Education, would like to thank all the science
faculty members of the Colleges of Education, Paro and Samtse and teachers from different schools for their valuable
contributions towards the development of this book. Our sincere gratitude also goes to Royal Society for Protection
of Nature, Ministry of Agriculture, Ministry of Health, Ministry of Economic Affairs, and other relevant agencies
for their unfailing support, starting from the development of the Science Curriculum Framework to the production
of science textbooks and manuals.
Our sincere appreciation to all the sources of pictures that are used in this book.
Advisors
Sangay Zam, Secretary, Ministry of Education, Thimphu
Tshewang Tandin, Director General, DAHE, Ministry of Education, Thimphu
Kesang C Dorji, Director, DCRD, Ministry of Education, Paro
Researching and writing
Wangpo Tenzin, Principal Curriculum Officer, DCRD, Ministry of Education, Paro
Surjay Lepcha, Curriculum Officer, DCRD, Ministry of Education, Paro
Lecturers of College of Education, Royal University of Bhutan, Samtse and Paro
Teachers from schools
Proof Reading
Gopilal Acharya, Free Lance Editor, Thimphu
Amber Kumar Rai, Curriculum Officer, DCRD, Paro
Sharda Rai, Subject Specialist, BCSEA, Thimphu
Art Work and Layout
Surjay Lepcha, Secondary Science, DCRD, Paro
Sangay Tshering, Teacher, Drugyel HSS, Paro.
All rights reserved. No part of this book may be reproduced in any form without a written permission from
the DCRD, Ministry of Education, except for educational purposes.
ISBN 978-99936-0-370-2
Contents
Foreword
iii
Introduction
vii
To the students
viii
Chapter 1. Matter
1.1 What are Elements
1.2 Change of State
1.3 Properties of Solid
1.4 Properties of Liquid
1.5 Floating Liquids
1.6 Properties of Gas
Chapter 2. Physical Change
2.1 Natural and Man-made Changes
2.2 What are Physical Changes
2.3 Is Dissolving a Physical Change
2.4 Are Melting and Freezing Physical Changes
2.5 Are Boiling and Evaporation Physical Changes
Chapter 3. Separating Solid Mixtures
3.1 Types of Solid Mixtures
3.2 Separating by Hand Picking
3.3 Separating by Sieving
3.4 Separating by Winnowing
3.5 Magnet as Separator
Chapter 4. Frictional Force
4.1 Force that Opposes
4.2 Frictions in Everyday life
4.3 Increasing Friction
4.4 Decreasing Friction
Chapter 5. Light and Sound
5.1 What Makes White
5.2 Bouncing Light
5.3 Musical Sound
5.4 How Sound Differs
5.5 Making Music
Chapter 6. Electricity and Magnetism
6.1 How We Generate Electricity
6.2 Connection in Series
1
1
3
6
10
12
14
17
17
19
22
24
26
31
31
33
35
37
39
42
42
44
46
48
52
52
55
57
59
61
65
65
68
6.3 Static Electricity
6.4 Which Part of the Magnet is Strong
6.5 Like Poles and Unlike Poles
Chapter 7. Energy
7.1 What is Energy
7.2 Forms of Energy
7.3 Saving Energy
7.4 Things that save Energy
7.5 Energy Change
Chapter 8. Characteristics of Living Things
8.1 Animal Characteristics
8.2 Plant Characteristics
8.3 Individuals are Different
8.4 Variation in Plants and Animals
8.5 Life Cycle of Animals
Chapter 9. Green Plants
9.1 Parts of a Plant
9.2 Functions of Root
9.3 Functions of Stem
9.4 Parts of a Flower
9.5 Functions of different Parts of a flower
Chapter 10. Living Things and their Environment
10.1 Food Chains in a Habitat
10.2 What is Food Web
10.3 Saving Threatened Plants and Animals
10.4 Disappearing Forest
10.5 Protecting Habitat
Chapter 11. Nutrition and Human System
11.1 Food for Health
11.2 Eating Habits
11.3 Human Transport System
11.4 Skeleton and Muscle
Chapter 12. Our Moon
12.1 The Moon
12.2 Moon in the First Week
12.3 Moon in the Second Week
12.4 Moon in the Third Week
12.5 Moon in the Fourth Week
73
75
77
81
81
83
86
88
90
93
93
95
97
99
101
104
104
106
108
110
113
116
116
119
122
126
128
132
132
134
136
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147
148
INTRODUCTION
To state in general terms, science is the study of everything around us, including our body. These includes
things like plants, water, soil, stones, wind, air and everything around us. We study about our body, how
each part of our body works, and how can we lead a healthy life. We develop a good understanding of
our world and about ourselves by observing the characteristics of things around us and their patterns by
actively engaging in the processes of doing science. This is fundamental to the accumulation of scientific
knowledge and skills that are indispensable for the well-being of people and the natural and social environment in which we live, and which we must treasure and conserve for the future generations. The volume
of scientific knowledge with which we live in this world, can be attributed to the hard work of many people
whom we call scientists.
Science is the knowledge of the world developed through human activities and used by people as ways of
improving life. Machines, simple or complicated, help people to do work easily. The contribution of science in the field of medicine and technology has always been a boon for the entire living organism on this
Earth. At the same time, the accelerated pace of development in the fields of science and technology also
brings drastic changes on the Earth in the form of climate changes and human conflicts. The school science
learning, therefore, should equip young minds with the scientific knowledge and skill to make educated
decisions in their everyday life. The scientific knowledge and skills developed through the learning of science are vital as these help people to be critical thinkers, and to realise that their actions in the environment
and society should be based on a sound scientific ideas and knowledge. This is important for people to take
good care of the environment and create a peaceful and prosperous society.
The Primary Science books for Classes IV to VI are critical in laying a sound foundation for the study of
science. With this in mind, the science textbooks for these classes contain a variety of learning activities,
each embedded with the basic scientific concepts and ideas instrumental in helping the learners to make
good sense of the world around them. The basics that the learners acquire in these classes serve them as
stepping stones to pursue higher studies in the field of science.
Unlike in the past, learners now should take a shared responsibility in their learning. It is the right of every
learner to know how they are assessed, how they can improve and how they are promoted to the next higher
grade. Toward the improvement of learners’ learning, learners should also know, among others, to choose
the best ways of studying. Therefore, this book contains a brief description of how they will be assessed,
and how they can organize their self studies by adopting study skills and strategies that suit them best.
Finally, what makes a person good learner is his or her commitment to participate actively in the teaching
learning process, rather than being a complacent listener awaiting for the teachers do science for him or her.
Primary Curriculum Division
Department of Curriculum Research and Development
vii
To the Students
No book, by itself, can make a learner gain knowledge and skills unless the learner meaningfully engages
himself or herself with its contents. This science book has a variety of topics to help you understand about
your bodies, about the world around, and be aware of different issues that people confront in their day to
day life. Each topic has several activities that you are required to do in fulfilling the learning objectives
outlined in the syllabus.
As such, the textbook has the following components.
I.
Textbook content
The textbook is arranged in the following sequence.
1. Test Yourself: Set of questions provided will recapitulate the earlier ideas and scientific concepts
learnt or known and also determine the knowledge already acquired on the topic.
2. You already know: This is to check what you already know about the topic to be taught. This is to
ensure that your teacher takes into consideration of your prior knowledge and experiences in planning
the teaching.
3. You will learn: This lists the expected learning objectives to be achieved in the lesson. At the end of
the lesson, you can use this list to evaluate your learning.
4. Learning activities that you must do: This provides scientific information and describes how the
learning activities should be carried out, either individually or in group, and things needed for each
activity.
5. Check your progress: Here, questions are given to test your understanding of the topic.
6. Think again: This part is to check your learning of the chapter. It has different type of questions to
test your learning in terms of scientific knowledge, skills, and values and attitude towards science and
the society.
7. Do you know: Where-ever relevant, there is additional information provided as “Do you know” to
add to your general knowledge in science. This will not be tested.
8. Community involvement: To vary the teaching process, where-ever relevant, people from the locality
are invited to take science classes to share the local knowledge on various topics. This is to help you
keep abreast of the local knowledge toward conserving the local knowledge and practices which, if
not preserved, can disappear from the society.
9. Model Question Paper: The model question paper with the sample answers is also provided at the
end of the textbook to help you to understand the type of questions you may expect in the summative
assessment. This also provides the cue of the range of cognitive levels of learnings, skills, and the
values and attitudes that the science curriculum is expected to provide.
II.
Learning activities that you must carry out
For effective learning, you will be asked to take the responsibility of your learning by actively participating
in all the teaching learning processes.
i.
Class work and homework
Regular class work and homework are given for you to practise and apply the scientific knowledge,
skills, and values and attitudes in making sense of the physical phenomena around you and, how
science affects your life and the society. Class work is a planned learning activity related to the lesson
taught that you will carry out in the classroom during the teaching period under the supervision and
guidance of the teacher.
Homework is a task given to you to be completed at home. Homework includes problems to be
solved, reading to be carried out, writing to be completed or other skills to be practiced. The work
viii
given should be done on your own.
ii.
Quizzes and debates
Quizzes and debates will be conducted on the specific topics, either as formal or informal activities,
coordinated by the science teacher. These activities are crucial as they will develop your analytical
and critical thinking to enhance your scientific general knowledge of facts and events of the scientific
world.
iii.
Group work and class presentation
Working in groups with your friends provide a context in which you help each other to achieve
the common goals. Group works, as the form of social work provide a constructive experience
of membership in a group, so that you develop further as individuals and be able to contribute
to the life of the community. You will be asked to work in groups and make presentations on a
regular basis so that you develop all the dimensions of the social skills that a productive citizen
must possess, and at the same time, provide your teacher the opportunity to assess your scientific
knowledge, skills and values and guide you on day to day basis.
iv.
Immediate interaction with peers and teachers
Your interaction with peers and teachers is an integral part of the teaching learning process. It helps
in promoting mutual trust and understanding. At the same time, your interaction with peers can help
the teachers to identify your learning needs and, accordingly provide necessary guidance for the
improvement of learning in all the learners.
v.
Experiments and exhibitions
Science experiments are scientific procedures undertaken to make a discovery, test a hypothesis,
or demonstrate known facts, while science exhibitions are public displays or demonstrations of
the workings and the benefits of science. Scientific experiments and exhibitions provide you the
opportunity to translate the scientific knowledge, skills and values into your everyday life and the
environment. Other benefits of doing them, include the development of skills to design experiments,
projects, scientific devices, information gathering, and communication of your work by using
various communication tools.
vi.
Field trips or excursions
Field trips or excursions are trips by a group of students to the places away from their normal
classroom environment. The purpose of the field trip is usually for the observation of natural and
scientific phenomena in the real field for first hand experiences outside the classroom activities in
relation to the topics taught in the science classes, or to carry out investigation or science project
works of your interest. The primary science curriculum requires you to collect information from
the community through the science learning activities, such as case study, investigation, survey, or
industrial visit, so that the teaching of science can be done in context to the local knowledge and
practices. The teachers can also use this to assess your ability to demonstrate the use of scientific
processes to gather information, investigate, and explore the natural world, collect data, interpret
and communicate your thoughts in varieties of ways.
vii. Project works and science journal or scrap book
Taking up a project work is one of the ways to practice the application of scientific concepts,
ideas and skills. The very purpose of including project work in the primary science is to provide
you with the opportunity to explore and extend your scientific knowledge and skills beyond the
classroom. Through project work, you learn various scientific techniques and skills including the
data collection, analysis, experimentation, interpretation, evaluation, drawing conclusion, and to
communicate the findings and observations to others in the most effective ways.
Journaling is a process of writing down of interesting scientific observations of scientific phenomena
ix
and events that you witness in and around the classroom or in the natural setting with insightful
reflection. It is a powerful way to help you develop the skills of recording the natural or scientific
events and phenomena by using the appropriate scientific language, and analyze their observations
to gain more insights into the scientific concepts, ideas and principles. It is also a window for the
learners to express their emotions in the form of creative display and narration about the materials
collected and entered in their journals.
A scrapbook is a book, in which you will collect the scientific clippings, specimens, study samples,
art works, articles, pictures, photographs related to science, which are of your own interests. Writing
a journal and making a scrapbook can be a great fun and engaging. It helps you become creative
and self-reflective as you write and keep records of the scientific events and observations of natural
phenomenon that you come across and interact with in your day to day life.
viii. Library researching
III.
The school library is a store of knowledge and ideas, which are used by all as the means to clarify
doubts, gain additional information and ideas on the specific topics, and seek guidance on the
conduct of experiment and project work. However, the search for information and ideas, call for the
skills on browsing and scheming for the needed information and ideas. Since science is all about
knowing oneself and the environment around, the science classes are liable for many questions of
what, why and how that may emanate from the learners everyday experiences, as they attempt to
probe deeper into the learning of science. Many intriguing questions can transcend the scope of the
textbooks or the teaching by the teachers and, most often, the teachers may not have the answers.
Therefore, the library facility is indispensable for any school to encourage learners to research the
information in the library. This primary science textbook has activities which demands you to do
small scale information search in the school library, so that you inculcate the skills of library study,
both for the academic excellence and for the meaningful use of the leisure.
Mode of Assessment
You will be assessed throughout the academic year by using the continuous formative and summative
assessment modes of assessments. This is important in order to monitor your progress in learning and to
help teachers to understand the efficacy of their teaching in the class. The following modes of assessments
are emphasised in the primary science.
1.
Continuous Formative Assessment (CFA)
This is a continuous process of assessing your problems in learning and the specific learning needs that you
and your peers have, so that your teacher can put in place the necessary remedial measures in improving
your learning. It also enables your teacher to understand, what teaching methods and materials work best.
You are not graded in CFA as it is mainly to monitor progress and provide you with necessary feedback
vital to enhance your learning.
You will be continuously assessed by using the varieties of techniques based on the criteria and the format
provided in the Science Teacher Guide. The suggested techniques to assess you through CFA are as follows:
i.
Class work and homework
Regular class work and homework are given for you to practise and apply the scientific knowledge,
skills, and values and attitudes in making sense of scientific world. In the process of completing
your classwork and homework, your teacher will assess your conceptual learning.
ii.
Self and peer assessment
This is one of the techniques of assessing your own learning or your peers. For such an assessments,
the teacher should ensure that the learning environment is friendly and supportive to encourage
students to be honest in providing constructive feedback in their own work and their peers. However,
x
the teacher will need to moderate the assessment done either by the individual learner or by the
peers.
iii.
Quizzes and debates
Quizzes and debates will be conducted on the specific topics to assess your conceptual knowledge
and understanding, and the level of scientific language developed in you and your peers. They can
be conducted as formal or informal activities.
iv.
Group work and class presentation
Working in groups with your friends provide a context in which you help each other to achieve
the common goals. Group works, as the form of social work provide a constructive experience of
membership in a group, so that you develop further as individuals and be able to contribute to the life
of the community. You will be asked to work in groups and make presentations on a regular basis,
so that you develop all the dimensions of the social skills that a productive citizen must possess. At
the same time, they provide your teacher the opportunity to assess your scientific knowledge, skills
and values, so that your teacher guides you on day to day basis.
v.
Immediate interaction with students
Your interaction with peers and teachers is an integral part of the teaching learning process. It helps
in promoting mutual trust and understanding. At the same time, your interaction with peers can help
the teachers to identify your learning needs and, accordingly, provide necessary guidance for the
improvement of learning in all the learners. This technique is particularly important to assess your
progress in the development of scientific and social skills, values and attitudes.
vi.
Experiments and exhibition
Science experiments are scientific procedures undertaken to make a discovery, test a hypothesis, or
demonstrate known facts, while science exhibition is a public display or demonstration of scientific
skills. Since the quality of the conduct of experiments and science exhibitions are guided by the
level of the knowledge and attitudes of the learner, this may serve as one of the good techniques to
assess your understanding of the scientific knowledge, skills and values.
vii. Observation of your conduct
Through the interaction and observation of every student’s action and attitude during the group
work and individual work, teacher comes to know the innate talent and weakness of every learner.
The information derived from the observation also helps the teacher to plan, implement, assess and
evaluate the teaching learning process. In the primary science curriculum, this technique is vital to
assess your ability to demonstrate the essence of working scientifically and your behavioral conduct
in the classroom.
viii. Field trip or excursion
Field trips or excursions are trips undertaken by a group of students to a place away from their
normal classroom environment. The purpose of the field trip is usually the observation of natural and
scientific phenomena in the real field, in order to provide you with the first hand experiences outside
their classroom activities. The primary science curriculum mandates for learning activities like case
study, investigation, survey of the natural phenomena, industrial visits or to collect information
from the community. Through the conduct of field trip or excursion, the teacher can assess your
ability to demonstrate the use of the scientific processes in gathering information, investigating and
drawing conclusion, and to explore in the natural world about the scientific events and phenomena
in the locality or in the region.
xi
2. Continuous Summative Assessment (CSA)
This is a continuous process of grading the student’s performances and achievements. Based on their performances, the teachers provide feedback for improvement. It also enables the teachers to understand what
teaching methods and materials work best. In this mode of assessment, you are graded and provided feedback, so that your learning is improved.
The techniques to assess the students through CSA are as follows:
i.Homework
The homework assigned to you must be completed with utmost diligence and integrity, as the quality
of your work can provide valuable information about your learning as well as the effectiveness of
the teaching strategies used in the class. As said earlier, your homework tasks may include to solve
problems, do reading and writings or other skills to be practiced. It is mandatory for teachers to
assess homework with grading at least once for every chapter and necessary feedback provided.
The cumulative marks obtained by you will be reflected in the progress report at the end of each
term.
Your homework in CSA is assessed based on the following criteria:
Criteria for home work
Name of
student
Total
Marks
Criteria
Completion
(4)
Accuracy (4)
Presentation
(4)
Creativity &
originality (4)
Submission
date (4)
(20)
Karma
....
ii. Chapter end test
A pencil and paper test is conducted at the end of each chapter. This is mainly to assess students’
conceptual understanding of the topic. However, it is important to balance the items selected for the
test with the inclusion of questions involving concepts, skills and values and attitudes. The chapter
end test is graded, and the cumulative mark is reflected in your progress report for each term.
iii.
Journal and Scrapbook
Writing a journal and making a scrapbook is an individual activity which reflects his or her attitude
and skills of organising things, and the types of innate talents an individual student possesses. It
helps students become creative and self-reflective as they write and keep records of the scientific
events and their observations of the natural phenomena, with which they interact in their day to day
life. The teacher will assess your journal and scrapbook only at the end of the year by using the
criteria given below and the rubrics provided in the Teacher Guide.
NB: Students should not include acids, corrosive substances, degradable and other flammable materials
as their entries in their journal and scrap book.
Criteria for the journal and scrapbook
Criteria
Name
Cover design
(4)
Format (4)
Entries (4)
Dorji
...........
xii
Presentation
(4)
Creativity (4)
Total
marks (20)
iv. Project Work
Project work helps the students learn to design, plan, and piece together many separate ideas and
information into a coherent whole. It provides an opportunity to explore and be familiar with a
variety of investigation processes in order to acquire the knowledge and skills, and to foster a
positive attitude towards science and the environment.
The product of the project work must be inclusive of write-ups, illustrations, models or collection
of real objects. The extent of the project work for each class is guided by the minimum number of
words suggested for each class, but not restricted by it.
Class IV
- minimum of 300 words.
Class V
- minimum of 450 words.
Class VI
- minimum of 600 words.
The teacher will use the rubric provided in the Teacher Guide to assess your project work. Viva voce is a
must to authenticate the originality of the work.
The students’ project work will be assessed based on the following criteria:
Criteria for project work assessment
Criteria
Name
Content
(4)
Presentation
(4)
Viva
voce
(4)
Process
(4)
Originality
and creativity
(4)
Submission
date(4)
Total
marks
(24)
Dorji
.......
v. Observation of your conduct
Through the observation of students’ conduct and behaviour, both inside and outside the classroom,
teachers can easily gauge the development of students’ scientific and social skills, values and
attitudes. These dimensions of learning can neither be captured by the pencil and paper test nor
the homework. In the primary science curriculum, this technique is vital to assess your ability to
demonstrate the essence of working scientifically and the scientific values and attitudes that you
have developed over the period of time through science learning.
Observation, either as incidental or planned activity, will be carried out throughout the teaching
learning process.
Observation of student’s conduct is important, mainly to:
• assess the student’s level of participation, cooperation, and responsibility in the learning
processes.
• assess the student’s behavioural conduct with teacher, friends and community.
• assess the student’s display of work ethics, honesty, integrity, and sincerity.
• check the demonstration of concerns towards oneself, others and environment.
To effectively use this technique, the teacher must maintain a record of the personal traits of
individual student gathered through: immediate interaction with students, conduct of science
experiment and exhibition, project work execution, classwork, and the field trips.
The teacher will use the rating scale to assess your display of scientific values and attitude throughout
the learning processes. The average marks obtained will be reflected in your progress report.
xiii
Perseverance (4)
Teacher’s comments
Total (40)
Concern for environment
(4)
Intellectual drive (4)
Honesty in scientific observation (4)
Punctuality (4)
Empathy for others (4)
Responsibility (4)
Name
Curiosity for exploration (4)
Criteria
Respect for others views (4)
Class:
Participation in learning
activities (4)
Sample rating scale for recording the marks for observation
Dawa
Pema
Sangay
............
3. Summative assessment
The summative assessment is used to assess the student’s cumulative level of performances and achievements
in terms of their conceptual knowledge, understanding of the scientific processes, and values and attitudes
towards science. The techniques of such assessments include the term end and end of year examinations
with the weighting of 20 and 30 marks respectively. In SA, you are graded and marks reflected in your
progress report.
IV. Assessment and Topic-wise Weightings
i. Assessment weighting
Term 1
SA
Weighting
10
10
5
Weighting
breakup
Term
Exam
20
45
SK
WS
SV
10
10
5
Observation of
students
SV
Total
Grand
total
55
100
SA
Journal and
scrap book
WS
CSA
Total
Observation of
students
SK
Project work
Areas
HW=5, Chapter
end test=5
CSA
Term 2
HW=5, Chapter
end test=5
Term
Assessment
type
Annual
Exam
30
NB:
1. CFA should be conducted as continuous assessment throughout the teaching learning processes without grading the
students.
2. SK: Scientific knowledge; WS: Working scientifically; SV: Scientific values and attitudes
xiv
ii. Topic-wise time allocation and weighting for Class V
Sl. no
1. Matter
2. Physical Change
3. Separating Solid
Mixtures
4. Frictional Force
5. Light and Sound
6. Electricity and
Magnetism
7. Energy
8. Characteristics of
Living Things
Maximum
time required
(mins)
Sub-topics
Weighting
(%)
1.1 What are Elements
1.2 Change of State
1.3 Properties of Solids
1.4 Properties of Liquids
1.5 Floating Liquids
1.6 Properties of Gas
2.1 Natural and Man-made changes
2.2 What are Physical changes
2.3 Dissolving a Physical change
2.4 Melting and Freezing Physical Changes
2.5 Are Boiling and Evaporation Physical Changes
80
120
120
80
40
120= 560
80
120
40
120
120=480
1.25
1.88
1.88
1.25
0.62
1.88=8.76
1.25
1.88
0.62
1.88
1.88= 7.51
3.1 Types of Solid Mixtures
3.2 Separating by Hand-Picking
3.3 Separating by Sieving
3.4 Separating by Winnowing
3.5 Magnets as Separators
4.1 Force that Oppose
4.2 Frictions in Everyday life
4.3 Increasing Friction
4.4 Decreasing Friction
5.1 What makes White
5.2 Bouncing Light
5.3 Musical Sound
5.4 How Sound Differs
5.5 Making Music
6.1 How We Generate Electricity
6.2 Connection in Series
6.3 Static Electricity
6.4 Which Part of the Magnet is Strong
6.5 Like and Unlike Poles
7.1 What is Energy
7.2 Different forms of Energy
7.3 Saving Energy
7.4 Things that save Energy
7.5 Energy Change
8.1 Animal Characteristics
8.2 Plant Characteristics
8.3 Difference between Plants and Animals
8.4 Individuals are Different
8.5 Variation in Plants And Animals
8.6 Life Cycles of Some Animals
80
120
120
80
120= 520
80
80
80
120=360
120
120
80
120
120=560
120
160
80
120
120= 600
80
120
120
80
120=520
80
80
80
80
120
120= 560
1.25
1.88
1.88
1.25
1.88= 8.14
1.25
1.25
1.25
1.88=5.63
1.88
1.88
1.25
1.88
1.88= 8.77
1.88
2.50
1.25
1.88
1.88= 9.39
1.25
1.88
1.88
1.25
1.88=8.14
1.25
1.25
1.25
1.25
1.88
1.88=8.76
xv
Total
Weighting
(%)
9
8
8
6
9
9
8
9
9. Green Plants
10. Living Things and
their Environment
11. Nutrition and
Human System
12. Our Moon
9.1 Parts of a Plant
9.2 Functions of Root
9.3 Functions of Stem
9.4 Parts of a Flower
9.5 Functions of different Parts of a flower
10.1 Food Chains in a Habitat
10.2 What is Food Web
10.3 Saving Threatened Plants and Animals
10.4 Disappearing Forest
10.5 Protecting Habitat
11.1 Food For Health
11.2 Eating Habits
11.3 Human Transport System
11.4 Skeleton and Muscle
12.1 The Moon
12.2 Moon in the First Week
12.3 Moon in the Second Week
12.4 Moon in the Third Week
12.5 Moon in the Fourth Week
120
120
80
120
120=560
120
120
120
80
160= 600
120
120
120
160=520
120
80
80
80
160= 520
6360
1.88
1.88
1.25
1.88
1.88= 8.77
1.87
1.87
1.87
1.25
2.50= 9.36
1.87
1.87
1.87
2.50=8.11
1.87
1.25
1.25
1.25
2.50=8.12
100%
9
9
8
8
100%
The actual teaching weeks, excluding all the activities and holidays is 23, which is equivalent to 6440 minutes or
161 periods of 40 minutes in a period.
V. Study Skill
Good study habits are important for success in school. Knowing how to study effectively fosters feelings
of competence, develops positive attitudes, and helps you realize how well one can do in school and in the
life. Good study habits also lay the groundwork for successful work habits as an adult.
You need to discover the best study system that fits your learning style, and use that system regularly. The
basic study skills that any teacher can emphasize for primary school children may include the following.
i. Developing good study habits
• Select a well-lighted place free from distractions. Remember to study alone to avoid disturbances.
• Study at a desk or table with a straight-back chair. Avoid the use of sofas as you may fall asleep. Set
a time to study.
• Set aside one or two hours of study time after school hours. Follow this timing regularly. Prepare a
timetable for studying. Start following the timetable according to the plan.
• Revise the daily lessons. Do not put off studying for a later date. To make the study session less
painful, take a 5 to 10 minutes break after every 20 to 30 minutes of study.
• The lessons taught must be revised and reflected upon on daily basis. This is crucial for children to
ascertain their understanding of the days’ lesson and to clarify their doubts with remedy measures
from the teachers.
• Study when most alert.
• The key to successful study is choosing the most efficient time when one’s mind is fresh and alert.
Generally, students may retain more information if the study session is followed by a sleep. But long
periods between study and sleep may tend to erase facts from memory.
xvi
ii. Sharpening your memory
• Pay attention.
• Concentrate on what one is studying. Do not let the mind drift away by different things one may see.
• Learn to make the information memorable so that one will not forget it easily. There are various
ways to make the information memorable. For example: repetition, mnemonics, and pictures and
diagrams.
• Repeating a new fact loudly will make it stay in mind for a long time. Mnemonics are memory
devices that help you remember things. One way is to take the first letter of each word to make a
new word to remember a long list of things. For example, while learning about the colours that make
up the spectrum, it is easy to remember it by the word VIBGYOR (V for violet, I for indigo, B for
blue, G for green, Y for yellow, O for orange and R for red), which is formed by taking out the first
letter of each colour in sequence. Another way of remembering things is by drawing pictures and
diagrams of the concepts.
• Correlate new facts and concepts with the previous knowledge or with the environment. Instead of
being satisfied with what one has learned, take some time to think and try to connect this information
with the ones that one has already learned.
iii. Improving your test-taking abilities
• Before the test date, go through the class notes to revise what you have learned. Ask your parents,
teachers or elders if you have any doubts at the time of the revision of notes.
• Remember to eat well and sleep well before the test. Always be on time for the test. Do not get
nervous. Remain calm. Read the directions carefully. Answer the easy questions first. Keep the
difficult ones at the end. Ask the teacher on duty for any clarification of the question. Once one
finished answering, read the answers again to check whether all the questions have been completed,
including writing your name on the answer paper.
iv. Becoming a critical thinker
• One of the first requirements of critical thinking is to participate actively in the process of acquiring
information. Do not accept everything that one hears and reads, but analyze and reflect on what one
learns.
• One may encounter many new terms, which are the foundation bricks in understanding various
subjects. Without a clear understanding of definitions of new terms, one may be unable to master the
subject, and will not be able to think clearly and critically.
• Our world is full of events. To understand them, one needs to probe with questions of what, why and
how about the phenomena and analyze the evidences critically.
xvii
Chapter 1
Matter
1.1 What are Elements
Test Yourself
1.
2.
3.
4.
5.
You already know:
particle arrangement in matter.
You will learn:
A.
Name three forms of matter.
Give two examples of matter.
What happens when liquid is heated?
Give two examples of gas.
Liquid on heating changes to _____and on cooling changes to ____.
definition of element.
You learnt that matter is made of particles.
If a matter is made of only one kind of particle, it is known as an element.
Some examples of elements are gold, silver, iron, copper, oxygen and hydrogen.
Many elements join together to
form other substances.
Example, water is made of two
elements, hydrogen and oxygen.
Therefore, water is not an element.
It is a compound.
Water molecule
Hydrogen
Hydrogen
Oxygen
1
Matter
B.
Go to your school library.
List down ten elements and display in the classroom.
Do You Know?
Until the year
1800, people
thought water
was an element.
Check Your Progress
i. What is an element?
ii. Choose the elements from the following list.
carbon, sugar, hydrogen, milk, gold, salt
http://www.nyu.edu/pages/mathmol/textbook/compounds.html
http://www.chem4kids.com/files/elem_perTable.html
2
Matter
1.2 Change of State
Test Yourself
1.
2.
3.
4.
5.
Give two examples of element.
Is water an element?
What is an element made of?
What happens to butter when it is heated?
How can you change water into ice?
You already know:
solids have definite shape and volume.
liquids have definite volume but no definite shape.
gases have neither definite volume nor shape.
You will learn:
A.
melting and freezing.
evaporation and Condensation.
Matter can change from solid to liquid and liquid to gas.
Matter can also change from gas to liquid and liquid to solid.
Some solids can change directly to gas and back to solid.
These processes are called change of state.
These changes are usually caused by heating or cooling.
When solids melt they change to liquid.
This process is called melting or fusion. Heat a spoon of butter in a
container. The butter melts.
What makes butter melt?
3
Matter
Figure 1.1 given below shows the processes of change of state.
Gas
nd
bl
im
at
io
n
en
sa
Ev
Su
bl
im
at
io
n
Su
Co
tio
ap
n
or
at
io
n
Melting
Freezing
Solid
Liquid
Figure 1.1 Change of state
Work in groups
Study the Figure 1.1.
Copy and complete Table 1.1 given below:
Table 1.1
Change of state
Process of change
1. Solid to liquid
2. Liquid to gas
3. Liquid to solid
4. Gas to liquid
5. Solid to gas
6. Gas to solid
B.
Your teacher will demonstrate this experiment.
What happens to water when it is heated?
Cold plate
Name the process.
What happens to the vapour when it touches the cold plate?
Name the process.
4
Matter
C.
Your teacher will demonstrate the process of sublimation.
Cotton
Inverted funnel
Evaporating dish
Solid (Ammonium chloride)
Tripod
Heat
Figure 1.2
List down the materials used by your teacher.
What happens to the solid on heating?
What happens to the vapour when it touches the cold
surface of the funnel?
What is collected on the walls of the inverted
funnel?
Do You Know?
Evaporation
takes place at all
temperatures.
Why is the funnel plugged with cotton?
Give two examples of solid used in our daily life that undergoes sublimation.
Check Your Progress
i. What is condensation?
ii. What is sublimation?
http://www.chem4kids.com/files/matter_states.html
http://www.school-for-champions.com/science/matter_states_changing.htm
5
Matter
1.3 Properties of Solid
Test Yourself
1. Why is liquid a matter?
2. Give one condition to change solid to liquid.
3. The change of state from liquid to gas is called ___________ and
the change of state from liquid to solid is called ____________.
4. Do all solids have same shape?
5. State one characteristic of a solid.
You already know:
matter can be solid.
matter can be liquid.
matter can be gas.
You will learn:
shape and volume of a solid.
particle arrangement in a solid.
A. You have learnt that solid, liquid and gas are three states of matter.
These states of matter are different in many ways. This is because they have
different properties.
Work in groups
You will need:
metal block
metre rule
Look at the metal block.
What is its shape?
Measure the length, width and height of the metal block with the metre rule.
Record your reading in Table 1.2 given below in your notebook.
6
Matter
Table 1.2
Length (cm)
Width (cm)
Height (cm)
Find the volume of the metal block using your readings.
B. Volume = length x width x height
There is another method of finding the volume of solid by using measuring
cylinder and water.
1mL = 1cm3 or 1cc (cubic centimetre)
Work in groups
Take extra care while
handling glass apparatus
You will need:
measuring cylinder
metal block
water
thread
Pour some water in a measuring cylinder.
Record the level of the water. Make sure you read the
lower meniscus.
Tie the metal block with a thread.
Slowly lower the metal block into the water.
Record the level of the water again.
7
Matter
Copy and complete Table 1.3.
Table 1.3
Level of water in mL
Observation
Before putting the metal block (initial
reading)
After putting the metal block (final
reading)
What is the volume of the metal block in cm3?
Carry out an experiment to find the volume of a stone.
Write about:
what you needed.
what you did.
Read the volume of water in it.
Slowly lower the stone in the water.
Record the volume of the water again.
What did you find?
[Volume of stone= volume of water and stone – volume of water without
stone]
Volume of an object can be measured by measuring the volume of water
displaced by the object when immersed in it.
Volume of an object = volume of water displaced.
C. Work in groups
You will need:
metal block
beaker
Put a metal block into beakers of different sizes.
What happens to the shape of the metal block when placed in different beakers?
What happens to the volume of the metal block when placed in different beakers?
8
Matter
D. All solids, liquids and gases are made of tiny particles.
Particles cannot be seen with our naked eyes.
Look at the Figure 1.3 given below.
Do You Know?
Scientist have
now discovered
fourth state of
matter called
plasma.
Particle
Solid
Figure 1.3
How are the particles arranged in a solid?
Describe the properties of a solid.
Check Your Progress
i. The Figure 1.4 given below shows the arrangement of particles in a ________ ,
because the particles are ________________________.
Particles
Figure 1.4
ii. Is our body solid? Why?
http://kent.skoool.co.uk/content/keystage3/chemistry/pc/learningsteps/SLGLC/launch.html
http://www.kwoodward.dsl.pipex.com/sfa/slg.htm
9
Matter
1.4 Properties of Liquid
Test Yourself
1.
2.
3.
4.
5.
Does solid have fixed shape?
How are particles arranged in a solid?
How will you find the volume of a regular metal block?
What is the shape of a liquid?
How are the particles arranged in a liquid?
You already know:
properties of solid.
You will learn:
A.
shape and volume of a liquid.
particle arrangement in a liquid.
Properties of liquid are different from the properties of solid.
Work in groups
You will need:
Measuring cylinder, beaker, conical flask, flat bottom flask, U-shaped tube, round bottom flask, large size test tube, water trough, glass bottle, and water.
Collect glass containers of different shapes and sizes.
Pour equal volume of water into each container with the help of the measuring
cylinder.
Observe the containers with water in Figure 1.5 and correct the following
sentences.
Figure 1.5
10
Matter
i.
ii.
iii.
Different containers contain different volume of water.
The levels of water in different containers are the same.
The shape of water is same in all the containers.
Does liquid have a fixed shape? Why?
Now, take a measuring cylinder and measure the volume of the water in each
of the above containers separately.
Does liquid have a fixed volume?
B.
Do You Know?
Look at the Figure 1.6 given below.
Glass is a super
cooled liquid
Particle
Liquid
Figure 1.6
How are particles arranged in a liquid?
Describe the properties of liquids.
Check Your Progress
i. Is milk a liquid? Why?
ii. Describe the particle arrangement in liquid.
http://www.bbc.co.uk/schools/scienceclips/ages/8_9/solid_liquids.shtml
11
Matter
1.5 Floating Liquids
Test Yourself
1. Have you seen leaves floating in water? Why do you think they float?
2. Why does stone sink in water?
3. Give an example of a liquid floating over another liquid.
4. Why does oil float on water?
5. Does milk float on water? Why?
You already know:
sinking and floating solids.
You will learn:
sinking and floating liquids.
A.
Work in groups
You will need:
vegetable oil
honey
water
measuring cylinder
cork
test tube
test tube stand
Take a measuring cylinder.
Measure equal volume of vegetable oil, honey and
water.
Pour them into a test tube.
Close the mouth of the test tube with the cork.
Shake the test tube.
Place it in the test tube stand and watch what
happens.
12
Matter
Draw a picture of the test tube with the liquids.
Label the layers of the liquid.
Which liquid is the lightest?
Which liquid is the heaviest?
Check Your Progress
i.
In places where kerosene lamp is used, people usually add water in the
kerosene lamp when the oil is less. Why?
ii.
If you add a drop of blue ink in a test tube of water, what will you observe?
http://chemistry.about.com/od/chemistryactivities/a/densitycolumn.htm
http://e2bn.skoool.co.uk/content/primary/science/states_of_matter/index.html
13
Matter
1.6 Properties of Gas
Test Yourself
1.
2.
3.
4.
5.
Give two properties of a solid.
Give two properties of a liquid.
How are particles arranged in a liquid?
Is water vapour a gas?
Why are gases lighter than liquids of same volume?
You already know:
properties of solid.
properties of liquid.
You will learn:
shape and volume of gas.
particle arrangement in gas.
A.
Properties of gas are different from the properties of solid and liquid. Air is a
mixture of gases.
Work in groups
You will need:
balloon
thread
Blow a balloon and tie it with the thread.
What is the shape of the air inside the balloon?
What will happen to the shape of the air when the balloon is
gently squeezed or twisted?
Now in the same group, try this.
You will need:
matchbox
paper
glass jar with lid
14
Matter
Light the paper and drop it into a glass jar. Cover it with a lid.
What happens to the smoke inside the glass jar?
What is the shape of the smoke?
Take extreme care when
working with matches and
flames.
Remove the lid.
What happens to the smoke now?
Does the shape of the smoke change when the lid is
removed?
Does the volume of the smoke change when the lid
is removed?
Describe the shape and the volume of the gas.
B.
Look at the Figure 1.7 below.
Gas particles
Gas
Do You Know?
The particles in solids,
liquids and gases are
always moving but at
different speed. This
movement is due to
the difference in the
energy of the particles.
Figure 1.7
How are particles arranged in gas?
Describe the properties of gas.
Check
Your Progress
i. Gas does not have fixed shape and volume. Explain.
ii. The smoke from the school kitchen oven spreads over the entire kitchen. Why?
15
Matter
Think Again
1. Write true or false for the following statements.
i. Matter is made of particles.
ii. Solids take the shape of the container.
iii.The change of ice into water is called evaporation.
iv.An element is made of single substance.
v. Particles are closely packed in gas.
2. Write two differences between sublimation and evaporation.
3. Describe water cycle using the following words.
evaporates, sea, condenses, rises, river, rain, water vapour, heat
4. Design a model showing particle arrangement of solid, liquid and gas.
5. Why does butter float in suja?
6. How will you find the volume of an irregular solid which floats on water?
http://chemed.chem.purdue.edu/genchem/topicreview/bp/ch4/properties2.html
http://phet.colorado.edu/en/simulation/gas-properties
16
Chapter 2
Physical Change
2.1 Natural and Man-Made Changes
Test Yourself
1. List three natural things.
2. Name some of the things built by man.
3. What is a change?
4. What changes do you observe when a mango ripens?
5. What are the changes that occur when a raw egg is boiled?
You already know:
change of state.
You will learn:
natural changes.
man-made changes.
A.
Many changes happen around us.
Leaf changes its colour and a chick turns into a hen.
Changes take place not just around us, but also within us.
You grow from a baby to an adult. You grow in height. Your weight increases.
These changes are called natural changes because these changes happen
naturally.
Give three more examples of natural changes that
you see in your day-to-day life.
Besides natural changes, many changes are brought
about by humans. Construction of road, building a
house, felling of trees are some examples. Changes
brought about by humans are called man-made
changes.
Give three more examples of man-made changes.
17
Physical Change
B.
Given below is a list of changes that you see happening around us.
Plants growing, cooking food, change in weather, making suja, making ice in a
refrigerator, burning of wood
Burning of wood
Making ice
Making Suja
Plants growing
From the list of changes given above, sort them into natural and man-made
changes.
Copy and fill in Table 2.1 given below.
Table 2.1
Natural change
Man-made change
Check Your Progress
i. Name three natural changes that take place in a growing plant.
ii. Define man-made change with two examples.
Do You Know?
All changes
involve energy.
http://www.edinformatics.com/math_science/p_change.htm
http://e2bn.skoool.co.uk/content/primary/science/changes_temp_or_
perm_1/index.html
18
Physical Change
2.2 What are Physical Changes
Test Yourself
1. What is a natural change?
2. Water exists in three states. Name them.
3. Give one example of change that is temporary.
4. Is melting of wax a physical change? Why?
5. Give one example of change that is permanent.
You already know:
natural and man-made changes.
You will learn:
physical changes.
A.
Ice melts into water when heated. Water freezes back to ice when it is cooled.
This is an example of a reversible change. All reversible changes are temporary.
Milk can be changed into curd, but curd cannot be changed back into milk. This
is an example of an irreversible change. All irreversible changes are permanent.
Take a sheet of paper.
Fold it to make a toy aeroplane.
Unfold the toy aeroplane.
Do you get back the same paper?
Has any new substance been formed during the change?
Is the identity of the paper lost during the change?
Is the change reversible or irreversible?
Is the change permanent or temporary?
B.
Work in groups
You will need:
sugar crystal
mortar and pestle
watch glass
spatula
19
Physical Change
water
beaker
glass rod
measuring cylinder
Do not taste any chemicals
in the laboratory.
Take a spatula of sugar crystal in a watch glass.
Study its colour.
Add the sugar crystals in a beaker containing 20mL of
water.
Stir it with the help of a glass rod.
Copy and complete Table 2.2 given below.
Table 2.2
Characteristics
Sugar crystal
Colour
Taste
Soluble or insoluble
Now, crush the sugar crystal into powder using mortar and pestle.
Place the sugar powder in a watch glass.
Study its colour.
Add powdered sugar in a beaker containing 20mL of
water.
Stir it with the help of a glass rod.
20
Physical Change
Copy and complete Table 2.3 given below.
Table 2.3
Characteristics
Powdered sugar
Colour
Taste
Soluble or insoluble
Has any new substance been formed when sugar crystals are crushed into
powder?
Has the identity of the sugar crystals been lost when crushed into powder?
The sugar crystals have changed its shape into powdered sugar crystals.
However, there is no new substance formed and the identity of the sugar
remained the same. This type of change is called physical change.
C.
Carry out an experiment to show that no new substances are formed during a
physical change.
Write about:
what you needed.
what you did.
what you observed.
Do You Know?
http://ezinearticles.com/?Easy-Elementary-ScienceProjects-3
http://e2bn.skoool.co.uk/content/primary/science/
changes_temp_or_perm_2/index.html
Check Your Progress
i. Define physical change.
ii. Give two examples of a physical change.
21
The water we drink has
been circling around
in the water cycle for
millions of years. This
means the same water
exists now on the Earth
which was there during
the time of dinosaurs.
Physical Change
2.3 Is Dissolving a Physical Change
Test Yourself
1. State two properties of physical change.
2. Give two example of physical change.
3. Name two solids that are soluble in water and two solids that are
insoluble in water.
4. What happens to soluble solids when it is added to water?
5. How can you get back the salt from salt solution?
You already know:
characteristics of physical change.
You will learn:
A.
dissolving is a physical change.
You have learnt about soluble and insoluble substances. For example, sugar
dissolves in water. Therefore, sugar is a soluble substance.
Work in groups
You will need:
matchbox
tripod stand
wire gauze
evaporating dish
teaspoon
spirit lamp
water
salt
measuring cylinder
glass rod
Take 15mL of water in an evaporating dish.
Add one teaspoon of salt.
Stir it to dissolve.
22
Physical Change
Heat the solution until the water is completely
evaporated.
What do you observe?
Is dissolving of salt in water a physical change?
Explain.
Take care when working with
matches and flames.
Do not touch any heated object.
Check
Your Progress
i. Explain the term dissolving.
ii. Why is dissolving considered a physical change?
http://acswebcontent.acs.org/scienceforkids/index.html#Dissolving
23
Physical Change
2.4 Are Melting and Freezing Physical Changes
Test Yourself
1. What is a physical change?
2. Define melting.
3. Define freezing.
4. Why is melting of ice a physical change?
5. What are the sources of water for the streams and rivers in Bhutan?
You already know:
melting and freezing.
You will learn:
A.
changes taking place during melting and freezing .
When solid changes into liquid, it is called melting.
When liquid changes into solid, it is called freezing.
Freezing turns a liquid into a solid
Melting turns a solid into a liquid
Work in groups
You will need:
evaporating dish
candle wax
tripod stand
matchbox
sprit lamp
wire gauze
tongs
Do You Know?
Addition of impurities usually
lowers the freezing point.
Take some candle wax in an evaporating dish.
Heat it over the tripod stand for three to five minutes.
What do you observe?
24
Physical Change
B.
Now, remove the evaporating dish from the tripod stand and cool it.
What do you observe?
Has any new substance formed during the process?
Has the identity of the candle wax lost during the process?
Is it reversible change or irreversible change?
Is the change permanent or temporary?
Carry out an experiment using hydrogenated vegetable oil to show that
melting and freezing is a physical change.
Write:
what you needed.
what you did.
what you observed.
Be careful with the heated
hydrogenated vegetable oil
Is melting and freezing of hydrogenated vegetable oil a physical change? Why?
Check Your Progress
i. Differentiate between freezing and melting.
Freezing
Melting
ii. What happens when water freezes?
http://www.chemteam.info/Matter/PhysicalChemChanges.html
25
Physical Change
2.5 Are Boiling and Evaporation Physical Changes
Test Yourself
1. What is evaporation?
2. What is the use of thermometer?
3. What is the normal boiling point of water?
4. What happens to water when it boils?
5. How do our clothes dry?
You already know:
melting and freezing as physical changes.
You will learn:
changes taking place during boiling and evaporation.
A. You might have seen water boiling in a container.
Boiling is the rapid vaporization of liquid on heating.
The temperature at which liquid starts to boil is its boiling point.
Predict the boiling point of water in your school campus.
The boiling point of water is ________________
Work in groups
You will need:
thermometer
tripod stand
wire gauze
matchbox
spirit lamp
beaker
clamp stand
water
measuring cylinder
stop clock
The bulb of the thermometer
should not touch the bottom of the
beaker while heating.
26
Physical Change
Pour 100mL of water in a beaker.
Arrange the setup as shown in Figure 2.1.
Thermometer
Beaker
Water
Figure 2.1
Measure the temperature of the water every three minutes until water begins to
boil.
Copy and record your observations in Table 2.4 given below.
Table 2.4
Temperature (oC)
Time (minute)
0.0
3.0
6.0
9.0
12.0
15.0
...
...
Boiling point of water at your school campus is ______________
27
Physical Change
Draw a line graph representing change in temperature against time.
What does the graph show about the time and temperature?
Has any new substance formed during the boiling?
Has the identity of water lost during the boiling?
Is boiling a physical change?
B.
Your teacher will demonstrate this experiment.
Cold water
Condensed water
Water vapour
Hot water
Take extreme care when working
with matches and flames. Do not
touch any heated object.
Heat
Observe carefully.
Name various processes that are taking place.
Are evaporation and boiling physical changes? Explain.
Check Your Progress
i. Differentiate between evaporation and boiling.
ii. Miss Dema kept a beaker of water in sunshine for a week. The level of water
decreased every day. Why do you think the level of water decreased?
28
Physical Change
Think Again
1. Choose the correct answer:
i. Which of the following is a reversible change?
a. Cooking food.
b. Dissolving salt in water.
c. Making curd.
d. Rusting of iron.
ii. Growth of a child is an example of
a. chemical change and natural change.
b. physical change and man-made change.
c. man-made change and natural change.
d. natural change and physical change.
iii. Which is a physical change?
a. Growth of plants.
b. Melting of snow.
c. Curd formation.
d. Burning of papers.
iv. The example of man-made change is
a. ripening of fruit.
b. formation of cloud.
c. construction of road.
d. growth of a baby.
v. Which is a natural change?
a. Blooming of flowers.
b. Cutting down trees.
c. Burning firewood.
d. Making a cake.
29
Physical Change
2.
We often feel cold immediately after taking bath. Explain.
3.
Why does morning dew disappear after the sunrise?
4.
Is the formation of ice from water a physical change? Why?
5.
Blowing a balloon is a physical and reversible change. When the balloon bursts,
it is also a physical change. Give more examples of physical change.
6.
Draw a water cycle and indicate all the physical processes taking place in it.
7.
Dorji blows air into a red balloon and then squeezes out the air from it. Explain,
why it is a physical change.
30
Chapter 3
Separating Solid Mixtures
3.1 Types of Solid Mixtures
Test Yourself
1.
2.
3.
4.
What is solid-solid mixture?
Give one example of solid-solid mixture.
How are solids different from each other?
Give two examples of mixtures containing solids of different colours.
5. In what ways are solid-solid mixtures categorised?
You already know:
solid-solid mixtures.
You will learn:
types of solid mixtures.
A. You have learnt that stone in rice is a solid-solid mixture.
Name some other solid-solid mixtures which you have learnt.
Solid-solid mixtures are of various types depending upon the nature of solids
forming the mixture.
Solid-solid mixtures are classified based on:
a. Weight – heavy or light.
Example, mixture of rice and husk.
b. Colours- colour of the substances.
Example, mixture of grain and peas.
c. Size and shape - big or small.
- various shapes.
Example, maize and rice.
Give one more example for each type of solid-solid mixture.
31
Separating Solid Mixtures
B.
Work in groups
Collect four different solids of different colours and make as many solid-solid
mixtures from it.
Display your mixtures in your classroom.
How many mixtures could you make?
Can they be separated?
Check Your Progress
i. How do you classify solid-solid mixtures?
ii. What type of solid-solid mixtures do people use in the construction of
house?
Do You Know?
Your school bell
is a solid-solid
mixture. It is
brass, which is
made up of copper
and zinc.
32
Separating Solid Mixtures
3.2 Separation by Hand Picking
Test Yourself
1.
2.
3.
4.
5.
You already know:
different types of solid-solid mixtures.
You will learn:
A. State two properties of solid.
Give one example of solid-solid mixture based on colour.
Why do we need to separate the components of mixtures?
How can you separate stones from rice?
What is hand picking?
separation by hand picking.
For separating the constituents of a mixture we make use of their properties like
colour, size, shape, weight, solubility, melting point, boiling point, quantity, etc,.
Study the Figure 3.1.
What method of separation is
shown in Figure 3.1?
What properties of the mixture
shown in the picture enable them
to be separated by this method?
Figure 3.1
B. Let us investigate whether all solid–solid mixtures can be separated by hand
picking.
Work in groups
You will need:
gravel
teaspoon
rice
33
Separating Solid Mixtures
maize
sugar
salt
watch glass
Take a teaspoon each of the given solids and make the following mixtures in a
watch glass.
Mixture of salt and sugar.
Mixture of gravel and rice.
Mixture of rice and maize.
Mixture of sugar and rice.
Try separating the above mixtures using your hand.
Copy and complete Table 3.1 given below.
Table 3.1
Mixtures
Can be separated by hand picking
Yes
No
Salt and sugar
Gravel and rice
Rice and maize
Sugar and rice
Which mixtures could you separate easily? Why?
Which mixtures are difficult to separate? Why?
Check Your Progress
i. When can hand picking be an effective method of separation?
ii. What kind of mixtures do you separate by hand picking at home?
34
Separating Solid Mixtures
3.3 Separation by Sieving
Test Yourself
1. Give an example of mixture which can be separated by hand
picking.
2. Is hand picking an easy method to separate a mixture of maize and sugar?
3. Why is the method of hand picking not used for separating all
types of mixtures?
4. How can you separate a mixture of husk and flour?
5. What is sieve used for?
You already know:
separation by hand picking.
You will learn:
A.
sieving as a method of separation.
Look at Figure 3.2 given below.
Figure 3.2
What is shown in the pictures in Figure 3.2?
What are they usually used for?
Sieve is used for separating small particles from
the big particles.
This method of separation is called sieving.
35
Do not play in a
construction area. Falling
objects might injure you.
Separating Solid Mixtures
B. Visit any construction site.
Find out how sieve is used in the construction site.
Draw the picture of the sieve.
Show your diagram to your teacher.
Can you separate chalk powder and sand
using the same sieve? Explain.
Take care while working
with sharp tools.
C.
Work in groups
Make a sieve using locally available materials.
Use the sieve to separate mixtures.
Write about:
materials you used
how you made your sieve?
which mixtures can be separated using your sieve?
Do You Know?
Sieving is based
on the principle of
filtration.
Check Your Progress
i. Write the uses of sieve at home.
ii. Pema was given a solid mixture to separate by using a sieve. However,
he could not separate the mixture. Suggest what might be the possible
reasons for not being able to separate the mixture..
36
Separating Solid Mixtures
3.4 Separation by Winnowing
Test Yourself
1.
2.
3.
4.
5.
You already know:
Draw a picture of sieve.
Give two examples of mixture that can be separated by sieving.
Give two uses of wind.
What type of mixture can be separated by wind?
Name some of the things used to separate mixtures with the help
of wind.
separation by sieving .
You will learn:
winnowing as a method of separation.
A. Wind is used for various purposes like generating electricity and running wind
-mills. Wind can also be used for separating solid–solid mixtures. The method of
separating solid-solid mixtures using wind is shown in Figure 3.3 given below.
Have you seen this method of separation
practised in your locality?
This method of separation is practised in many
parts of our country.
Usually lighter solids are separated from heavier
ones with the help of wind. This method is
called winnowing.
Figure 3.3
37
Separating Solid Mixtures
B.
Work in groups
You will need:
dry leaves
gravel
plate
chair
Be careful while standing
on the chair.
Crush the dry leaves into pieces.
Mix it with gravel in the plate.
Go to an open ground.
Drop the mixtures slowly by shaking the plate.
What do you observe?
What properties of the substances in the mixture help the process of
separation?
Repeat the same process by standing on a chair.
Does the height affect the separation?
Where was the winnowing better? Explain.
Check Your Progress
i. What is winnowing?
ii. Mention the factors that affect winnowing.
http://www.topperlearning.com/student/video/NjE=/MTI2/CBSE/IX/Chemistry/Is%20
Matter%20around%20us%20pure/Separation%20of%20solid%20mixtures
38
Separating Solid Mixtures
3.5 Magnet as Separator
Test Yourself
1.
2.
3.
4.
5.
You already know:
winnowing as a process of separation .
You will learn:
A.
What agent is used for winnowing?
Name a mixture which can be separated by winnowing.
How will you separate a mixture of tea and tea leaves?
What is a magnet?
Give one use of a magnet.
magnet as separator.
Work in groups
You will need:
sand
iron filings
paper
bar magnet
Mix sand and iron filings on a sheet of paper.
Is it possible to separate the components of the mixture by hand picking? Why?
Is it possible to separate the components of the mixture by winnowing? Why?
Now, move a bar magnet over the mixture.
What do you observe?
The method in which magnet is used to separate the components of a mixture
is called magnetic separation. It is based on the property of a magnet to attract
magnetic substances towards it.
39
Separating Solid Mixtures
B.
Work in groups
Do You Know?
You will need:
bar magnet
pin
pieces of paper
nail
dry leaves
Electromagnet is
used to separate iron
scraps from plastics
and other metals in
industries.
Make three different types of mixtures which can be separated by using a
magnet.
What properties of components of the mixture make the separation possible?
What other separation methods can be used to separate your mixture?
Check Your Progress
i. Name some materials that are attracted by a magnet.
ii. Do you think a mixture of salt and sugar can be separated by a magnet?
Explain.
http://magnetic.ezinemark.com/magnetic-separators-with-its-best-uses-7d36d56fc1cc.html
40
Separating Solid Mixtures
Think Again
1. Match items of column ‘A’ with correct answers of column ‘B’
Column A
Column B
Winnowing
Iron from sand
Magnetic separation
Stone from rice
Hand picking
Flour from husks
Sieving
Mud from water
Filtration
Grain from husk
2. A pin falls into a heap of straw. Suggest an easy way of finding the pin.
3. Write one similarity and difference between filtration and sieving.
4. You are provided with a mixture of iron filings, sand and sawdust. Explain how you
will separate each of these substances from the mixture.
5. Which method is better for separating husk from wheat flour, sieving or winnowing?
Why?
6. What are the different properties that you would consider to separate a solid–solid
mixture?
7. Two students are trying to separate 50mL of mixture of sand and iron splinters
by using a bar magnet. Kinley Wangmo spreads the mixture on a sheet of paper.
Wangchuk tries with the heap of the mixture on the paper. Both use bar magnets
to remove the iron splinter from the mixture.
i. Whose method of separation do you prefer? Why?
ii.What precautions should you take while doing this experiment?
41
Chapter 4
Frictional Force
4.1 Force that Opposes
Test Yourself
1.
2.
3.
4.
5.
You already know:
force.
types of force.
You will learn:
A.
What makes an object move?
Name the force which pulls an object towards the Earth.
Name the force that exists when seated on a chair.
What happens when you rub your palm against a Table?
Why does a rolling marble stop after sometime?
friction as an opposing force. Friction is a force that tries to stop a moving object. It can slow down the
movement of an object or stop it from moving altogether.
Work in groups
You will need:
smooth board
bottles
cloth piece
Wrap one of the bottles with a cloth piece.
Lift the board to make an inclined plane as shown
in Figure 4.1.
Line up the bottles at the top of the board.
Release the bottles.
42
Frictional Force
Figure 4.1
Which of the two bottles reached the end of the board first?
Which one moved slowly? Why?
The bottle which reached the end of the board first experiences less friction.
The bottle wrapped with the cloth experiences more friction.
Check Your Progress
i. What is a friction?
ii. Why do we slip on a muddy path?
43
Frictional Force
4.2 Friction in Everyday Life
Test Yourself
1. We cannot climb wet poles easily. Why?
2. What force helps us to hold an object in our hands??
3. In which case do we experience more friction, while walking or
running?
4. Why are soles of shoes rough?
5. Where do we use friction in day to-day-life?
You already know:
friction.
You will learn:
A.
friction in everyday life.
Strike a coin to slide across a table. You will notice that the coin gradually slows
down and stops. Some force is acting on the coin making it to stop. This force
which is acting on the coin is called frictional force. Frictional force acts at the
surface of contact between the coin and the table.
Frictional force helps us to walk, run and write.
Work in groups
Discuss each activity given below in Table 4.1 and find out where the friction is.
Copy and complete Table 4.1.
One is done for you.
Table 4.1
Activity
Where is the friction?
Walking
Writing
Erasing the pencil mark
Moving vehicle
Rolling football
Between your feet and ground
44
Frictional Force
In the same group, come up with some examples of daily activities where friction
is present. Share your findings with the class.
Check Your Progress
i. What happens if you step on a banana peel? Why?
ii. Why are the handles of spade and sickle made smooth?
http://physics.tutorvista.com/forces/friction.html#
http://e2bn.skoool.co.uk/content/keystage3/Physics/pc/learningsteps/UFRLC/launch.html
45
Frictional Force
4.3 Increasing Friction
Test Yourself
1.
2.
3.
4.
5.
How did friction help you to do your homework?
Pema could not walk on a wet floor. Why?
Is there a friction when you are sitting on a chair?
Why do we sprinkle sand on a wet ground?
What will you do to walk on a slippery path?
You already know:
friction in everyday life.
You will learn:
A.
ways to increase friction.
Friction is felt when two surfaces slide against each other.
Rub your palm on the table.
Can you feel the friction?
The tyres of a vehicle have treads that help to increase friction and prevent from
slipping on roads. Similarly, your shoes have grooves to increase friction.
Treads
Grooves
Treads of tyres
Grooves of shoe soles
Work in groups
You will need:
chalk box
sandpaper
some books
46
Frictional Force
Make an inclined plane using books as shown in Figure 4.2.
Figure 4.2
Slide the chalk box over the inclined plane.
Now paste the sandpaper on the bottom of the chalk box.
Again slide the chalk box.
In which case does the chalk box slide slowly?
What can you conclude from this experiment?
BB
iscuss in pairs how you can increase friction in the
D
conditions given below in Table 4.2.
Copy and complete Table 4.2.
Table 4.2
Conditions
How to increase friction
Muddy footpath
Wet floor
Worn-out tyres
Check Your Progress
i. How can we increase friction?
ii. If you are planning to go for hiking on the mountains, what type of shoes
would you wear? Why?
http://www.bescientist.info/how-to-understand-the-concept-of-friction-in-physics/
47
Frictional Force
4.4 Decreasing Friction
Test Yourself
1.
2.
3.
4.
5.
Why is sandpaper used by a carpenter?
What will you do to climb faster on a pole?
Name the force which slows down the moving objects.
What helps a moving vehicle stop?
Why do trolleys have wheels?
You already know:
ways to increase friction.
You will learn:
ways to decrease friction.
Sometimes friction makes work more difficult. We need to find ways to
decrease it.
What happens if a hinge on a door is rusty and rough? Why?
One of the ways of reducing friction is by applying oil on the hinges.
A.
What are the other ways of reducing friction?
B. Friction as an opposing force can be measured by spring balance or Newtonmetre. This instrument is named after a famous scientist Sir Isaac Newton.
To pull 1 kg mass of an object you need 1 kg of force.
1kg => 1kgf
1kgf = 1000gf
48
Frictional Force
Work in groups
Do You Know?
You will need:
spring balance
box
stones
talcum powder or flour
Put a few stones inside the box.
Then place it on one end of the table.
Pull it to the other end with a spring balance.
Note the reading on the spring balance.
Now sprinkle talcum powder on the table.
Again pull it with the spring balance.
Note the reading.
49
Friction causes
wastage of
energy in all
machines! For
example, about one
fifth of energy used
in a car is wasted by
friction of the moving
parts.
Frictional Force
Copy Table 4.3 and record the readings.
Table 4.3
Set up
Force needed to pull ( in gf)
Box sliding on the table without
talcum powder.
Box sliding on the table sprinkled
with talcum powder.
In which case is greater force required to pull the box? Why?
Give another condition in which the force needed to pull the box is lesser than the force that you recorded in your investigation.
Check Your Progress
i. Why do we sprinkle talcum powder on a carom board?
ii. Why do we need to reduce friction?
iii. Yeshey’s father and mother are trying to move a box of grain from their
common room to the store room. They are finding very difficult to move it.
They have the choice of using straight and round firewood logs or gravels from
outside their house, if they wish. What will you suggest and why?
http://www.tutorvista.com/content/physics/physics-iii/motion-laws/reduce-friction.
php#polishing
http://www.tutorvista.com/content/physics/physics-iii/motion-laws/frictions.php#
50
Frictional Force
Think Again
1. Choose the correct answer
i. Force that opposes motion is called
a. magnetic force.
b. gravitational force.
c. frictional force .
d. electrostatic force.
ii. We can increase friction by
a. polishing.
b. oiling.
c. greasing.
d. making treads.
iii. Which of the following is the heaviest liquid?
a. Water.
b. Oil.
c. Kerosene.
d. Honey.
iv. Which one of the following is a disadvantage of friction?
a. Wearing out of the shoe sole.
b. Walking on the path.
c. Running on the ground.
d. Lighting a matchstick.
v. We add grease to
a. increase friction.
b. increase weight.
c. decrease friction.
d. decrease weight.
2. Why should we change worn-out tyres?
3. Give two examples where friction is useful.
4. Why is heat produced when we rub our hands together?
5. Why is it easier to write on a chalkboard than on a white board?
6. Give one example where friction is a hindrance.
51
Chapter 5
Light and Sound
5.1 What Makes White
Test Yourself
1.
2.
3.
4.
5.
Name an object which gives light.
What is the colour of the sky?
When do you usually see a rainbow?
How many colours do you see in a rainbow?
Why is light important?
You already know:
light travels in a straight line.
You will learn:
composition of white light. A.
In our daily life we see many different colours. Our houses, dzongs, lhakhangs,
and temples are painted with different colours. During tshechu, we see beautifully
coloured thangkas and thongdrels. Bhutanese wear ghos and kiras of various
colours. In nature, plants, flowers, birds, and animals are also of various colours.
Have you seen a rainbow?
Rainbow appears when it drizzles and the Sun shines at the same time. The light
coming from the Sun is white light. When the white light enters the raindrops it
gets separated into seven colours forming a rainbow. This is called dispersion.
52
Light and Sound
You can make your own rainbow
Work in groups
You will need:
mirror
bowl or tray
water
Put some water in a bowl.
Place the bowl in a bright sunlight.
Rest the mirror on the edge of the bowl as shown in the Figure 5.1.
Wall
Mirror
Bowl
Figure 5.1
Gently move the mirror till you see the colours on the wall.
How many colours can you see?
List down the colours you see?
How can you make the colour appear more distinct?
B.
Work in groups
You will need:
torch
compact disc
Design and carry out an experiment to show that white light is composed of
seven colours by using torch and compact disc.
Write about:
what you needed.
what you did.
53
Light and Sound
What you observed
What can you do to make the colours distinct?
Sunlight consists of seven colours: violet, indigo, blue, green, yellow, orange and
red (VIBGYOR). This set of colours make up a spectrum. When we combine
these colours, it looks white.
One way of showing that white light is composed of seven colours is by using
Newton’s disc.
C.
Work in groups
Make a Newton’s disc at home like the one given on the right.
You will need:
cardboard
pencil
a pair of scissors
crayons
protractor
compass
Take help from an adult.
Cut out a circle of 5cm radius from a cardboard.
Divide it into seven equal parts.
Colour each part as shown in the picture.
Insert the pencil through the centre of the circular
disc.
Spin your disc.
What can you see?
Draw your Newton’s disc.
How does the speed of the disc affect the colour?
Display your Newton’s disc in the class.
Check
Your Progress
i. How is rainbow formed?
ii. What is a spectrum?
54
Do You Know?
Isaac Newton was
the first scientist to
split white light into
seven colours using
a prism.
Light and Sound
5.2 Bouncing Light
Test Yourself
What is the composition of white light?
How is shadow formed?
Why can you see yourself in the mirror?
Why is a room with pink wall brighter than a room with brown wall?
5. We see objects in presence of light. Why?
1.
2.
3.
4.
You already know:
white light and its composition.
You will learn:
A
reflection of light. Sunlight reaches to us in a beam of light. This beam is composed of many rays
of light. For example, when you shine a torch you will see a beam of light.
Reflection
Work in groups
You will need:
mirror
stone
protractor (geometry instrument)
pencil
paper
Mirror
Figure 5.2
Stone
Draw two lines perpendicular to each other on a paper.
Place two mirrors exactly on the lines as shown in Figure 5.2.
Place a stone between the mirrors.
How many stones can you see in the mirrors?
Now, decrease the angle of mirrors slowly.
Be careful! Edges of
Is the number of stones seen in the mirror the
the mirror may cut your
same?
fingers.
What will happen if you increase the angle of
the mirrors?
55
Light and Sound
Light rays from the stone travel back and forth between the mirrors. This
bouncing of light is called reflection.
B.
Work in groups
You will need:
bucket
water
Take a bucket of water.
Let it stand still for a few minutes.
Now, look at water in the bucket without disturbing the water.
What can you see?
Next, gently disturb the water.
Again look in the bucket of water.
Is the reflection of your face the same? Why?
Uneven surface reflects light in all directions. Therefore, we do not get clear
image of an object. Even surface reflects light in one direction. Therefore, we get
a clear image of an object.
Reflection from an even surface
Reflection from an uneven surface
Figure 5.3
Check Your Progress
i. What is reflection?
ii. What type of surface reflects a clear image?
56
Light and Sound
5.3 Musical Sound
Test Yourself
1.
2.
3.
4.
5.
What causes sound?
What is vibration?
Name two musical instruments.
Which musical instrument do you like the most? Why?
What vibrates in the musical instrument that you like?
You already know:
name of few musical instruments.
You will learn:
musical sound. A. A pattern of sounds intended to give pleasure to people listening to it is called
music.
Musical instruments help us to make music.
Work in groups
You will need:
twine thread
sticks
Tie the ends of a thread to two sticks.
Pull the sticks apart to stretch the thread.
Pluck the thread with fingers.
Listen to the sound produced.
What will happen to the sound if you change the length of the string?
57
Light and Sound
Which length of the string makes sharper sound?
What would happen to the sharpness of the sound if the thread is replaced
with:
woollen thread
rubber band
metal wire
Check Your Progress
i. What is music?
ii. How can you increase the sharpness of a musical sound?
http://www.sciencekids.co.nz/sciencefacts/sound.html
58
Light and Sound
5.4 How Sound Differs
Test Yourself
1.
2.
3.
4.
5.
What is sound?
How does the sound from your teacher in the class reach your ears?
How does sound vary with distance?
How is sound produced by whispering and shouting different?
How is sound produced by different musical instruments different?
You already know:
musical sound.
You will learn:
A.
how sound differs.
Work in groups
You will need:
drinking glass
water
stick
measuring cylinder
notebook
A
B
C
D
E
Pour different amount of water into each glass.
Tap the glass with the stick.
Which glass makes the sharpest sound?
Which glass makes the most flat sound?
How will sound change if the glasses are covered with a notebook?
59
F
Light and Sound
B
Work in groups
You will need:
beakers of different sizes
rubber bands
Wind the rubber band around each beaker firmly as shown in Figure 5.4.
A
B
C
Rubber band
Figure 5.4
Pluck the rubber band at the mouth of the beaker.
Which beaker produces loud sound?
Which beaker produces faint sound?
How does the loudness of the sound change with
the size of the containers?
Musical instruments which have larger sound box
will have more air for vibration. When more air
vibrates, it will produce a louder sound.
Do You Know?
Whales in the ocean
sing to each other.
The sound of their
song can travel to a
distance of 800 km.
Check Your Progress
i. Why do you use bigger sound boxes during your school’s cultural events?
ii. How can you increase the loudness of sound?
60
Light and Sound
5.5 Making Music
Test Yourself
1.
2.
3.
4.
5.
You already know:
How can you decrease the loudness of the sound?
What is a sound box?
How is sound produced in a drangyen?
Where are bjaling and dhung used?
Name some religious musical instruments used during your local
tshechu.
different musical sound.
You will learn:
what makes music
A. The common musical instruments in Bhutan can be classified into the following:
Stringed instruments
In stringed instruments, sound is produced when the stretched string vibrates
between two fixed points on the instrument.
Some examples of stringed instruments are dramnyen, guitar, yangchen,
pchiwang, and violin.
Violin
Guitar
Dramnyen
Pchiwang
61
Yangchen
Light and Sound
Wind instruments
In wind instruments, air vibrates to produce sound. Examples of wind
instruments are flute, whistle, gezkang (slide whistle), trumpet, bjaling, dhung,
conch, etc,.
Conch
Flute
Bjaling
Whistle
Trumpet
Dhung
Percussion instruments:
In percussion instruments, sound is produced when you strike on the instrument.
For example, when you beat a drum with a stick, its membrane vibrates to
produce sound.
Examples of percussion instruments are drum, nga and tangti.
Drum
Nga
Tangti
Copy and complete Table 5.1 given below:
Table 5.1
Instrument
What vibrates?
Yangchen
Drum
Flute
Conch
Tangti
Guitar
62
Light and Sound
B.
Work in groups
Design and make one musical instrument.
Write:
what you needed.
what you did.
what you made.
Stage a musical show for two minutes in the class with the musical instrument
you have made.
Check Your Progress
i. Why is sound box important in a musical instruments?
ii. Name the type of instrument held by LhamoYangchenma (goddess of song
and music).
http://www.sciencekids.co.nz/experiments/makemusic.html
63
Light and Sound
Think Again
1. State whether the following sentences are true or false:
a. Trumpet is a percussion instrument.
b. Flute is a stringed instrument.
c. Sunlight is composed of seven different colours.
d. Even surface reflects light in all directions.
e. Sounds are produced when materials vibrate.
2. Write two uses of reflection in our day-to-day life.
3. List down the colours of the spectrum.
4. Name one instrument which does not have a sound box.
5. Describe the reflection of light from a mirror.
6. Why is music important for Bhutanese?
7. A student fills one bottle with water to half of its volume. In another, he fills it with
water to three fourth of its volume. Then he attempts to produce sound by blowing
air into them. Explain the sound produced in each case.
64
Chapter 6
Electricity and Magnetism
6.1 How We Generate Electricity
Test Yourself
1.
2.
3.
4.
5.
What are the sources of electricity?
What is the main source of electricity in Bhutan?
Name the device that uses sunlight to produce electricity.
Name some uses of electricity.
Name some power stations in Bhutan.
You already know:
we get electricity from water.
You will learn:
generation of electricity. A.
Our country has many hydropower stations where electricity is generated,
example, Chukha Hydropower Station. We do not use all the electricity generated
by our hydropower stations. We export electricity to other countries.
Can you name some more hydropower stations in our country?
We need lot of water to produce hydroelectricity. A dam is built across the river
to store water. The water from the dam flows into a tunnel with great speed. This
fast flowing water turns large wheels called turbines. The turning of the turbine
makes the machine called generator produce electricity.
The Figure 6.1 given below shows storage of water in dams.
Figure 6.1
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Electricity and Magnetism
Dam
Generator
Tunnel
Turbine
Water
Generation of electricity
Water
Turbine
Electricity produced
Why do we need to build a dam?
What makes turbine move?
What is produced from the generator?
Can the water that comes out of the turbine be used again? Why?
B. Study the graph in Figure 6.2 and answer the questions.
2011
2012
Figure 6.2
i. In which month is the maximum electricity generated? Why?
ii. In which month is the least electricity generated? Why?
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Electricity and Magnetism
C. The Figure 6.3 below show two other sources of electricity.
Windmill
Solar panel
Figure 6.3
In the windmill, wind is used to turn the turbine to generate electricity.
Solar panels convert energy from sunlight directly into electricity.
Water, wind, and sun are renewable sources of energy. They are clean sources of
energy and producing them do not result in pollution.
In some countries, non-renewable sources like coal and nuclear materials are
used to generate electricity. These sources cause pollution.
Check Your Progress
i. Describe briefly how electricity is produced in a hydropower station in
Bhutan.
ii. Why do we have more hydropower stations?
iii. Name two renewable sources of electricity.
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Electricity and Magnetism
6.2 Connection in Series
Test Yourself
1.
2.
3.
4.
5.
What is electric current?
What is an electric circuit?
When does electricity flow?
Where do you usually see a switch?
What is electric wire made of?
You already know:
simple connections.
You will learn:
switch.
series connection.
A. A switch is an electrical device. Turning off a switch breaks the circuit and the
flow of current stops. This is called open circuit. Turning a switch on completes
the circuit and allows the current to flow. This is called closed circuit.
Work in groups
You will need:
paper clip
bulb
dry cell
wires
Make a circuit as given below in Figure 6.4.
B
A
Figure 6.4
68
Electricity and Magnetism
B.
Connect a paper clip at point A and another paper clip at point B. Touch the
clips.
Observe what happens to the bulb.
Detach the clips and observe what happens to the bulb.
What is the function of the clips in the above experiment?
You will use this circuit in activity B.
Work in groups
You will need:
nail scissors dry stick rubber band plastic pen
copper wires
coin steel spoon papers
paper pins
aluminium foil
Use the same circuit that you have used in the above activity.
B
A
Now place the above materials in between the clips at points A and B in turn.
Observe carefully.
Copy and complete Table 6.1 given below.
Table 6.1
Materials used
Connects the circuit [Yes/No]
Scissors
Iron nail
Rubber band
Dry stick
Coin
Plastic pen
Aluminium foil
Steel spoon
Paper
Paper pins
Copper wire
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Electricity and Magnetism
Name the materials that make the bulb
glow.
Suggest two materials that can be used
to make switch.
Do not make your own switch for
your home circuit, because your
The materials that allow the current to
house circuit carries high voltage,
flow are called conductors.
which is very dangerous .
The materials that do not allow the
current to flow are called insulators.
Name the conductors used in the above activity.
Name the insulators used in the above activity.
C. Voltage is the difference in level of charge between the two ends of the cell, i.e
the positive end and the negative end. A common dry cell has a voltage of 1.5.
You can see the voltage written on the body of the cell.
The amount of voltage that an appliance require is usually written on the
appliance.
Work in groups
You will need:
dry cell
wires
torch bulb
bulb holder
paper clip
sellotape
Make a circuit as shown below in Figure 6.5.
Figure 6.5
What voltage is supplied to the circuit?
Observe the brightness of the bulb.
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Electricity and Magnetism
Turn off the switch.
Add one more cell as shown below in Figure 6.6.
Figure 6.6
Turn on the switch.
What voltage is supplied to the circuit?
What happened to the brightness of the bulb? Why?
Turn off the switch.
Now add one more bulb near the first bulb as shown below in Figure 6.7.
Figure 6.7
Turn on the switch.
Observe the brightness of both the bulbs.
What difference do you see in the brightness of the bulbs? Why?
Turn off the switch.
Add one more bulb near the second bulb.
Turn on the switch .
Do all the bulbs glow with the same brightness?
What happens if one of the bulbs is removed from the circuit? Why?
The kind of circuit in which the appliances (bulbs) are connected one after the
other in the same circuit is called series circuit.
In the series circuit, the voltage from the battery is distributed among the bulbs.
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Electricity and Magnetism
The bulb which is connected to the positive terminal of a battery receives the
maximum voltage. Therefore, it is the brightest.
Check Your Progress
i. Why do we use switch in the circuit?
ii. Why does the brightness decrease when you connect more bulbs in the circuit?
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Electricity and Magnetism
6.3 Static Electricity
Test Yourself
What is a conductor?
What is voltage?
What amount of voltage is supplied by an ordinary cell?
You hear a crackling sound made by clothes while removing
them. Give reason.
5. What is static electricity?
1.
2.
3.
4.
You already know:
series connection.
You will learn:
static electricity.
A. There is another kind of electricity that does not require circuit to flow. It is
called static electricity. During the rainy season you must have seen lightning
followed by thunder. Lightning is an example of static electricity.
Similarly, when we take off woollen or nylon clothes that we are wearing, sparks
and crackling sound are produced due to the charges developed by friction.
Therefore, static electricity is also called frictional electricity.
Work in pairs
You will need:
balloon
woollen cloth piece
plastic comb
jug of water
plastic pen
small pieces of papers
73
Electricity and Magnetism
1. Rub a balloon on a piece of woollen
cloth. You could use your gho or
kira. Rub it for one minute. Hold the
balloon up to the wall. Let go.
2. Comb your dry hair with a plastic
comb several times. Hold the comb a
few centimetres above your friend’s
head.
What happens?
What happens?
3. Rub the balloon on a piece of
woollen cloth. Hold it near running
water from a jug or tap.
4. Rub a plastic pen on a piece of
woollen cloth. Hold the pen very
close to small pieces of paper.
What happens?
What happens?
Rubbing the balloons, the pen and the comb build static electricity.
The static electricity pulls the hair towards the comb, the water towards the
balloon and the pieces of paper towards the pen.
Similarly, before a thunderstorm, static electricity builds up in the clouds which
escapes as a flash of lightning. When lightning strikes, it may start fire. It is
dangerous to be outside when there is lightning.
Check Your Progress
i. What is the difference between static electricity and current electricity?
ii. Give an example where you experience static electricity.
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Electricity and Magnetism
6.4 Which Part of the Magnet is Strong
Test Yourself
1.
2.
3.
4.
5.
Where do you find magnets at home?
Differentiate between magnetic and non-magnetic objects?
How does distance affect strength of attraction of the magnet?
Name different types of magnets.
Describe two characteristics of a magnet.
You already know:
magnet attracts magnetic materials.
You will learn:
A.
poles of a magnet .
Magnets have magnetic forces around them.
Work in groups
You will need:
iron filings
magnet
sheet of paper
plastic bag
Use a plastic bag as glove.
Spread a thin layer of iron filings on a sheet of paper.
Roll the magnet on the iron filings.
Write about your observation.
Which parts of the magnet attract more iron
filings?
Why do you use plastic bag as gloove?
The parts of the magnet that attract more iron
filings are called poles of the magnet.
75
Do not play with iron
filings. It might get into
your eyes and harm you.
Electricity and Magnetism
B.
Work in groups
Thread
You will need:
twine thread
bar magnet
chalk
compass
Figure 6.8
Hang the magnet with the help of thread as shown in the Figure 6.8.
Make sure the magnet is hung horizontally to the ground and can turn freely.
Wait for the magnet to stop moving.
With the help of magnetic compass, mark the end of the magnet pointing to the
geographical North as N.
Repeat one more time.
One end of the magnet always points North and the other end points South.
This is why the ends of the magnet are called North-seeking pole or North Pole
and the South-seeking pole or South Pole.
Check Your Progress
i. How many poles are there in a magnet? Name them.
ii. Which part of the magnet is strong?
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Electricity and Magnetism
6.5 Like Poles and Unlike Poles
Test Yourself
How many poles does a magnet have?
Which part of the magnet is strong?
What are like poles and unlike poles of magnets?
What happens when two magnets are brought closer to each
other?
5. Which pole of magnet attracts a pin?
1.
2.
3.
4.
You already know:
North pole and South pole of a magnet.
You will learn:
like poles and unlike poles.
A.
Similar poles are called like poles.
Opposite poles are called unlike poles.
Work in groups
You will need:
magnets
What happens when you put two magnets near each other as shown below in
Figure 6.9.
3
1
4
2
6
5
Figure 6.9
77
Electricity and Magnetism
After the experiment fill in Table 6.2 given below.
Table 6.2
Diagram No
Like/unlike poles
Attract or repels
1
2
3
4
5
B.
6
Which poles attract?
Which poles repel?
Work in groups
You will need:
thermocol
bar magnet
paper
pieces of stick
bowl
water
Make a boat out of thermocol.
Put a bar magnet inside the boat.
Attach a paper sail.
Let it float in a bowl of water.
Hold another magnet close to the boat.
What happens?
Change the pointing pole of the magnet towards the boat.
Explain what happens. Why?
78
Figure 6.10
Electricity and Magnetism
Check Your Progress
i. Identify the poles of magnets marked as X and Y.
X
South
Y
ii. Nima and Dawa are trying to find the geographical North. Each of the boy
hangs a bar magnet with threads. They suspend the magnets very close to each
other. What is wrong with their experiment?
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Electricity and Magnetism
Think Again
1. Fill in the blanks with correct words.
i. Like poles ______________and unlike poles _______________.
ii. Lightning is caused by___________________electricity.
iii.The south-seeking pole of a magnet is called________________.
iv._______________completes the circuit when we turn it on.
v. The ____________________is used to generate hydroelectricity.
2. How do we construct a series circuit?
3. Differentiate between conductor and insulator? Give an example each for a
conductor and insulator.
4. Narrate an incident where static electricity has been the cause of a disaster.
5. Why is hydroelectricity considered a clean energy?
6. Dorji, Tshomo and Yeshi made circuits as shown in Figure 6.11 below.
Paper Clips
Dorji
Tshomo
Paper Clips
Yeshi
Figure 6.11
i. Whose bulb will glow?
ii. What is wrong with the circuit in which the bulb does not glow?
80
Wooden pieces
Chapter 7
Energy
7.1 What is Energy
Test Yourself
1.
2.
3.
4.
5.
You already know:
What do we get from food?
Write two examples of energy giving food?
Is electricity and sound forms of energy? Why?
Clothes dry faster on a sunny day. Why?
In winter, why do you sit near the fire place or heater?
we need food to live, work and play.
You will learn:
definition of energy and what energy does.
A. You cannot see energy but you can see what it does. Energy from the Sun helps
to dry our clothes, vegetables, fruits, etc. Energy from firewood cooks food.
Energy from running water turns prayer wheel.
Work in groups
All the activities in Figure 7.1 given below are fueled by energy.
Burning fire
Aeroplane flying
Steaming soup
Radio playing
Ringing of bell
Figure 7.1
81
Lighted torch
Lightning
Prayer wheel rotating
Energy
Look at the above pictures in Figure 7.1. Sort and write the activities under the
following headings in your notebook.
Things that warm up
Things that move
Things that make sound
Things that produce light
What are the various uses of energy in the above pictures?
Now, explain energy in your own words.
Share your answer with the class.
Observe the jumble words in the circles.
work
do
the
Energy
is
to
ability
Using all the words, define energy.
Energy is measured in joules. The symbol used is J. However, energy in food is
measured in calories (cal).
Check Your Progress
i. What is energy?
ii. Write four examples of what energy does.
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Energy
7.2 Forms of Energy
Test Yourself
1.
2.
3.
4.
5.
What is energy?
What can energy do?
What is the unit of energy?
Why does a falling boulder crash a small tree?
What energy in water is used to generate electricity?
You already know:
definition of energy.
You will learn:
forms of energy.
A. Energy is required to do work. Different works require energy in different forms.
Investigate with a partner.
You will need:
torch
Copy and complete Table 7.1.
Table 7.1
Activity
What is produced?
Form of energy
Rubbing your hands
Switching on the torch
Clapping your hands
Name the activities where the forms of energy are produced as given below in
Table 7.2.
Table 7.2
Form of energy
Activity
Heat energy
Light energy
Sound energy
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Energy
B. There are other forms of energy.
Chemical energy is stored energy. It is found in food, fuels and batteries.
Foods, batteries and fuels
Potential energy is the stored energy due to the position or condition of the
object.
Ice, snow and water on high mountains
A stretched rubber band
Chemical energy and potential energy are both stored energy. What is the
difference?
Kinetic energy is the energy present in moving objects.
A bouncing ball
A running boy
A flowing river
Electrical energy is a form of energy that comes from electricity.
84
Energy
Electrical energy
Work in groups
Using the clues given in the box, find the forms of energy hidden in the word
puzzle. Do not mark in the text book.
computer, moving car, kerosene, bhukhari, girl singing, sun, stone on hillock
L
I
G
H
T
D
R
E
F
I
L
S
W
Q
H
V
C
X
L
G
J
S
N
E
R
C
E
F
O
E
D
R
O
Q
R
H
U
H
M
S
C
Y
N
U
W
K
W
E
Y
E
I
T
E
Q
N
E
I
E
I
F
P
M
R
K
G
D
R
N
R
M
A
J
N
I
T
S
B
T
E
Y
N
A
U
C
C
C
O
J
T
T
J
O
S
X
R
A
S
A
G
Y
I
L
M
D
H
W
L
P
A
L
List down all the forms of energy found in the puzzle.
What form of energy does a television use?
Check Your Progress
i. What form of energy will a rolling stone have?
ii. What form of energy is present in the following?
a. Ringing of a bell
b. Plate of rice
85
H
C
L
U
D
E
E
W
W
R
M
J
P
O
K
Q
A
X
F
L
G
F
P
O
T
E
N
T
I
A
L
G
F
J
Z
A
K
Q
O
X
F
L
G
F
Energy
7.3 Saving Energy
Test Yourself
1.
2.
3.
4.
5.
You already know:
What is potential energy?
What is the form of energy found in food?
Kinetic energy is possessed by a ____________ body.
Why is it necessary to switch off the light when not in use?
Why do your parents turn off the stove while not cooking?
forms of energy.
You will learn:
ways of saving energy.
A. We need energy for everything that we do in our lives.
All energy resources need to be used wisely.
Why do we need to be aware of how much energy we use?
Work in groups
Look at the pictures in Figure 7.2.
Figure 7.2
86
Energy
How is energy being wasted in the pictures in Figure 7.2?
How can you save energy in the pictures in Figure 7.2?
Take help of your parents. Make a list of at least five ways in which you can
save energy at home.
B. Vehicles need fuel like petrol and diesel . These come from oil found under the
ground. There is only a limited amount of oil under the ground. So we must save
and use them wisely.
Work in pairs
Find out the cost of a litre of diesel and petrol. A person uses 5 litres of diesel
in a day. How much will he spend in a week?
How can we save fuel?
We use electricity at school and at home. Find out:
where does it come from?
who pays for it?
how much is paid for it every month?
what can be done to stop electricity being wasted?
C.
Work in groups
Design and make a poster for saving energy. Display your poster in places like
classroom, library, market and at home.
Check Your Progress
i. How is energy wasted in your school?
ii. We should not waste energy. Why?
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Energy
7.4 Things that Save Energy
Test Yourself
1.
2.
3.
4.
5.
You already know:
ways of saving energy.
You will learn:
A.
Why do we save energy?
List some ways by which energy is wasted at home.
Suggest some ways of saving energy.
What is the advantage of using pressure cooker to cook food?
What is the advantage of using tube light over a bulb?
things that save energy.
We have to pay for every unit of energy that we use. Firewood, gas, petrol, diesel
and electricity are bought. If we use more energy, then we need to pay more. We
can save energy using different energy saving devices.
Work in groups
Look at Table 7.3 given below and find out how energy is saved in each case.
Table 7.3
Things that consume
more energy
Pot
Incandescent bulb
Things that consume
less energy
Pressure cooker
Tube light
88
How energy is
saved?
Energy
Things that consume
more energy
Things that consume
less energy
Car
Bicycle
Smokeless stove
Open stove
B.
How energy is
saved?
Work in groups
Discuss and list down some energy saving devices.
Explain how these things shown in Figure 7.3 save energy.
Compact Fluorescent Lamp (CFL)
Figure 7.3
Compact Fluorescent Lamp (CFL) uses less electric energy and generates less
heat. It lasts almost ten times longer than the incandescent bulbs.
Incandescent bulbs
Buy appliances and electronics with the ENERGY
STAR ® Label
More stars on the label imply more energy is saved.
Check Your Progress
i. List two appliances at your home which save energy.
ii. Why should we go for star-labelled electronic appliances?
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Energy
7.5 Energy Change
Test Yourself
Name different forms of energy.
Riding a bicycle is better than driving a car. Why?
Where do you get energy from to carry out daily activities?
What happens to the light energy absorbed by plants during
photosynthesis?
5. Explain the energy changes taking place when you put on a
television.
1.
2.
3.
4.
You already know:
You will learn:
A.
things that save energy.
energy change .
When you walk to school, deliver a speech in the morning assembly or plant a
flower in your school garden, you are changing energy from one form to another.
If you look around, you will notice many energy changes taking place. Energy can
be changed from one form to another forming an energy chain. The chemical
energy of the food you eat is changed into kinetic energy when you play or work.
And the energy chain is written as shown below.
Chemical energy
kinetic energy Let us study how energy changes from one form to another.
Work in groups
You will need:
candle
matchbox
Do not play with fire!
Light a candle. Observe carefully.
What form of energy is present in the candle?
What energies are formed when the candle burns?
Write the energy chain that occurs when you burn the candle.
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Energy
B.
Work in pairs
Study the pictures in Table 7.4. Copy and complete Table 7.4.
Table 7.4
Pictures
Energy chain
A girl playing guitar.
A boy kicking a ball.
Solar panel connected
to TV.
Water turning the prayer
wheel with bell.
Rubbing hands together.
Check Your Progress
i. Why is energy change important?
ii. Draw an energy chain for the generation of hydroelectricity.
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Energy
Think Again
1. Match items of column ‘A’ with correct answers of column ‘B’
Column A
Column B
Stretched rubber band
kinetic energy
A flying bird
ability to do work
Energy
chemical energy
Battery
saves energy
Smokeless stove
potential energy
2. Name three appliances used at home that saves energy.
3. Write the energy chain for the following cases:
a. battery powered radio.
b. lit torch.
4.
What is the importance of transformation of energy?
5. Suggest five ways of reducing the electricity bills.
6. Which one of the following would you prefer to use at home in order to save
energy? Why?
a. Incandescent bulb
b. Compact Fluorescent Lamp
7. Kinley winds the spring of a toy car and releases it on a smooth floor.
a. What does the toy car do? Trace the energy chain.
b. After covering some distance, the car stops. Why?
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Chapter 8
Characteristics of Living Things
8.1 Animal Characteristics
Test Yourself
1.
2.
3.
4.
5.
You already know:
animals are living things.
different types of animals live around us.
animals are useful to human beings .
You will learn:
A.
From the list given below, identify the living things:
pig, wood, mug, stone, cat, horse, chair
Name some animals which are helpful to us.
Why are all types of animals not found in your locality?
Animals move from one place to another. Why?
List similarities between a cow and a dog.
characteristics of animals
You may have pets or any other animal at your home. Write about them in your
notebook. Share to the class.
Dog
Cat
Horse
B. Characteristics are certain unique features of plants and animals.
Animals cannot prepare their own food. They grow but the growth stops after
certain age.
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Characteristics of Living Things
Work in groups
Go around your school campus and observe some animals. Write some more
characteristics of animals.
Write the names of the animals you observed against the characteristics
mentioned in Table 8.1 given below:
Table 8.1
Characteristics
Name of animals
Can move.
Can breathe.
Can reproduce.
Can grow.
From Table 8.1 given above, what can you conclude
about the characteristics of animals?
List down all the common characteristics in a chart
paper.
Display the chart in the classroom.
Do You Know?
Animals like cats,
dogs and horses
can turn their ears
towards sound
without having to
turn their head.
Check Your Progress
i. Ants and elephants are animals. Why?
ii. What do you mean by characteristics of an animal?
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Characteristics of Living Things
8.2 Plant Characteristics
Test Yourself
1.
2.
3.
4.
5.
Write some characteristics of animals.
Write one difference between plants and animals.
Write some common features of plants.
Animals depends on ___________ for food.
Do you see plants moving from one place to another? Why?
You already know:
plants are living things.
You will learn:
characteristics of plants.
A. Plants are living things. Green plants prepare their own food. They do not move
from place to place.
Go around your school campus and observe some plants. Write some more
characteristics of plants.
Write the names of the plants you observed against the characteristics mentioned
in Table 8.2 given below:
Table 8.2
Characteristics
Name of plants
Can prepare their own food.
Cannot move from place to place.
Can grow continuously.
Can reproduce its own kind.
From Table 8.2 given above, what can you conclude about the characteristics of
plants?
List down all the common characteristics in a chart paper.
Display the chart in the classroom.
95
Characteristics of Living Things
B. Collect a leaf from any of the plants you have listed. Make a leaf print in your
scrapbook.
Check Your Progress
i. Both grass and pine tree are plants. Support this statement with reasons.
ii. Why plants do not need to move from place to place?
Redwood trees
Do You Know?
The world’s tallest
trees are the coast
Redwood trees
found in California.
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Characteristics of Living Things
8.3 Individuals are Different
Test Yourself
State one difference between plants and animals.
Why cannot a fish live on land?
Name three types of trees.
How many varieties of dogs have you seen? How do they differ
from each other?
5. Every plant and animal in this world is different from each other.
Explain.
1.
2.
3.
4.
You already know:
animals are different in shape, size, colour, etc,.
You will learn:
differences among individuals.
A. Measure the height of each person in your class.
You will need:
chart paper
metre rule
pencil Cut a long thin strip of chart paper using scissors.
Paste it on the wall of your classroom.
Measure 1 metre from the floor with the rule and
mark it with the pencil.
Above 1 metre, measure in centimetres and make a
scale.
Let each person in the class stand against the scale.
Record the heights in Table 8.3 given below.
97
Characteristics of Living Things
Table 8.3
Range of Height (cm)
Tally
How many students
120-125
126-130
131-135
136-140
141-155
156 Make a bar graph to show the heights of the students in your class.
Which range of height has the maximum number of students?
Which range of height has the minimum number of students?
How many students are there in your height range?
You observe the difference in height between you and your friends. Other than
height you also have different weight, shape and size of your body compared to
your friend.
Similarly, there are differences in body characteristics among other animals and
plants belonging to the same group. For example, all cats do not look alike. They
differ in shape, size, colour, etc. These differences among individuals belonging
to the same group are called variations.
Check Your Progress
i. What is variation?
ii. What are the common variations that you observe among your family
members?
Do You Know?
Wolffia is the
world’s smallest
flowering plant.
Wolffia
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Characteristics of Living Things
8.4 Variation in Plants and Animals
Test Yourself
1. What are the ways in which you are different from your friends?
2. What are two factors that bring about variation in plants and
animals?
3. Why is variation important?
4. Write down the colours of flowers that you have seen.
5. Name the different types of dogs that you have seen.
You already know:
individuals are different.
You will learn:
variations in plants.
variations in animals.
A. Variation is common in nature. It helps the living organisms to adapt and
survive. It also helps to produce new varieties.
Work in groups
Visit a flower garden. Observe different kinds of flowers carefully.
Avoid plucking flowers unnecessarily.
Copy and complete Table 8.4 given below:
Table 8.4
Size of flower
Flower
(small/medium/
Colour of petals Number of petals
large)
Flower 1
Flower 2
Flower 3
Flower 4
Do all the flowers look alike? Why?
How would your school garden look like if all the flowers are the same?
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Characteristics of Living Things
B.
Work in groups
Choose one type of animals from the list given below.
cows, pigs, dogs
Go to the library and find as many varieties as you can of the animal that you
have chosen. Write one characteristic for each of the variety.
You can also ask your elders or visit RNR centre.
One example is shown below in Table 8.5:
Table 8.5
Type of animal
Varieties
i. Trout
ii. Catla
Fish
iii.Salmon
iv. Carp
v. Mackerel
Share your findings with other groups in your class.
Check Your Progress
i.
What variations do you see in plants?
ii. How does variation help animals?
Different kinds of rhododendrons
Do You Know?
As of now there
are 46 species of
Rhododendron
and 369 species of
orchids in Bhutan.
Different kinds of orchids
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Characteristics of Living Things
8.5 Life Cycle of Animals
Test Yourself
1. Name some animals which lay eggs.
2. Name some animals which give birth to young ones.
3. How do animals reproduce?
4. Name the young one for the following animals.
cow, dog, cat, goat
5. An organism that is full grown is called ________.
You already know:
living things reproduce.
You will learn:
life cycle of some animals.
A. Living things have the ability to produce its own kind. This process is called
reproduction. The process of an animal or a plant beginning life, growing and
reproducing is called life cycle. In animals, male produces sperm and female
produces ovum. The fusion of an ovum and sperm is called fertilisation.
Let us look at the life cycle of a bird in Figure 8.1.
The eggs hatch into chicks
Fertilised eggs
Chicks grow into adult birds
Figure 8.1
Hens lay fertilised eggs. The fertilised eggs hatch into a chick after incubation
for about 21 days. The chick grows into an adult bird.
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Characteristics of Living Things
How many stages are there in the life cycle of a bird? Name them.
B.
Work in groups
Go to the library.
Draw and describe the life cycle of a cow and a bird.
What is the difference between the life cycle of a bird and a cow?
Check Your Progress
i. Define the following:
a. life cycle
b. reproduction
c. fertilization
ii. Write down the similarities between the life cycles of a cow and a bird.
http://e2bn.skoool.co.uk/content/primary/science/variation/index.html
http://www.sciencekids.co.nz/gamesactivities/plantanimaldif.html
http://www.kidzone.ws/animals/lifecycle.htm
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Characteristics of Living Things
Think Again
1. State whether the following sentences are true or false:
a.
b.
c.
d.
e.
Plants grow throughout their life.
Animals cannot reproduce.
Animals can make their own food.
The human population shows variation.
All flowers have equal number of petals.
Nima and Dawa are brothers, yet they look different. Why?
Write three characteristics of plants.
What is the importance of variation in living things?
How are animals different from plants?
Draw and describe the life cycle of housefly.
Read the story of an organism given below.
I am an organism. I can breathe, reproduce and grow. But I can not move from place to place. What type of organism is am I?
8. An experiment is set up in the science class. A small plant is placed in a conical
flask. The conical flask is connected to a test tube that contains clean lime water.
After one day, students observe that the clean lime water contained in the test tube
turned milky indicating that the carbondioxide flowed into it. What characteristic
2.
3.
4.
5.
6.
7.
of the plant is demonstrated by this experiment?
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Chapter 9
Green Plants
9.1 Parts of a Plant
Test Yourself
1.
2.
3.
4.
5.
Plant is a living thing. Explain.
What do plants need for their proper growth?
Which part of a plant is brightly coloured?
Which part of a plant is usually green?
Name the part of the plant that normally grows underground.
You already know:
plants are living things.
You will learn:
parts of a plant.
A. Like human body, plants also have many parts.
Look at the plant in Figure 9.1.
Leaf
Branch
Shoot
Stem
Root
Root
Figure 9.1.
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Green Plants
The part of a plant above the ground is called shoot and the part below the
ground is called root. The shoot has branches, leaves, flowers and fruits. The
root has root hairs.
Work in pairs
Collect a plant with its shoot and root. Compare it with the plant given in Figure 9.1.
Identify the different parts of the plant.
Draw a labelled diagram of your plant.
Does your plant have some other parts that are not shown in the Figure 9.1?
Add them in your diagram.
B.
Mounting a plant.
Work in groups
Do You Know?
You will need:
a chart paper
duplicating paper
marker pen
sellotape
water
The first plant on the
earth was a water
plant. It lived in the
sea over 3000 million years ago.
Collect a plant with all its parts.
Gently wash the roots with water.
Spread the plant carefully on a duplicating paper.
Put some more papers on top of it and press gently to dry.
Mount it on the chart paper with the help of a sellotape.
Label the parts using a marker pen.
Write the names of your group members and display it in the class.
Check Your Progress
i. What do you call the part of a plant below the ground?
ii. What are the different parts of a shoot?
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Green Plants
9.2 Functions of Root
Test Yourself
1.
2.
3.
4.
5.
What is a shoot of a plant?
Name different parts of the shoot of a plant.
The part of the plant below the ground is called ___________.
Which part of a plant absorbs water from the soil?
Name some edible roots found in your locality.
You already know:
different parts of a plant.
You will learn:
functions of root.
A.
There are two main functions of a root.
Work in groups
Do You Know?
You will need:
test tubes
measuring cylinder
young leafy plant with roots intact
water
vegetable oil
marker pen
Mosses are the plants
which do not have
roots to absorb water.
They absorb water
through their leaves.
Take two test tubes and fill them with equal volume of water.
Put a young leafy plant with its roots in one of the test tubes.
Add ten drops of oil into both the test tubes and mark the levels of water.
Label the test tube with plant as Setup A and the other as Setup B.
Leave the setups out in the sun for three to four hours.
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Green Plants
Oil
Test tube
Water
Setup A
Setup B
What is similar between the two setups?
What is different about the two setups?
Why is oil added into the test tubes?
Leave the set ups for a few hours.
What do you observe in Setup A?
What do you observe in Setup B?
Give reasons for your observations in Setup A and Setup B?
What function of the root does the experiment show?
Roots also absorb mineral nutrients present in the soil.
B.
Let us find out the other functions of roots.
Where do plants usually grow?
Why is it difficult to uproot a plant?
Why is soil easily washed or blown away from a barren land?
Besides absorbing water and mineral nutrients, the root also holds the soil to
fix the plant in it.
Check Your Progress
i. What are the two functions of roots in plants?
ii.
Why do people plant trees in landslide prone areas?
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Green Plants
9.3 Functions of Stem
Test Yourself
1.
2.
3.
4.
5.
What are the two main parts of a plant?
Which part of the plant absorbs water?
What do you think will happen to plants if there are no roots?
Draw a stem with different parts.
What holds leaves and flowers in a plant?
You already know:
functions of root.
You will learn:
A.
functions of stem.
Stem has two major functions. One function is to hold up the leaves and flowers
of the plant.
Let us investigate the other function of the stem.
Work in groups
You will need:
herbaceous plant
red ink
water
blade
beaker
hand lens
Be careful while using
blade.
Take a herbaceous plant.
Cut its fresh leafy shoot under water.
Dip the cut shoot in a beaker containing red ink solution.
Keep the setup for two hours.
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Green Plants
Clamp stand
Herbaceous plant
Stained section of stem
Beaker
Red solution
Figure 9.2
Cut a thin circular section of the stem and observe using hand lens or microscope.
Why do we need to cut the stem under the water?
What do you see?
What can you say from the experiment?
The nutrients needed by the plants are present in the soil.
These nutrients are dissolved in water.
They are absorbed by roots and conducted to leaves by stem.
Check Your Progress
Do You Know?
i. Write two functions of a stem.
ii. Name three stems that grow underground.
http://www.crickweb.co.uk/ks1science.html
http://www.crickweb.co.uk/ks2science.html#
http://www.rabbitsabc.com/roots.html
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Stem of young
plants are green
and performs photosynthesis.
Green Plants
9.4 Parts of a Flower
Test Yourself
1.
2.
3.
4.
5.
Which is the reproductive part of a plant?
Write the names of any two flowers.
Name different parts of a flower.
Name the male parts of a flower.
Name the female parts of a flower.
You already know:
parts of a plant.
You will learn:
A.
parts of a flower.
The Figure 9.3 given below shows different parts of a flower. Refer Figure 9.3 and
carry out the following activities.
Stigma
Anther
Style
Ovary
Stamen
Petal
Filament
Sepal
Pedicel
Figure 9.3
Work in groups
You will need:
flower
forceps
hand lens
blade
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Carpel
Green Plants
Take a flower.
Remove all the sepals carefully using the forceps.
Do You Know?
Bamboo flowers
only once in its
entire lifetime.
What is the colour of the sepals?
How many sepals are there?
All the sepals together are called calyx.
Now, remove the petals from your flower.
What is the colour of the petals?
How many petals are there?
All petals together are called corolla.
Observe the stamen using hand lens.
Note that the stamen is made up of anther and filament.
Draw the stamen and label its different parts.
Now, observe the carpel using hand lens.
Note that the carpel is made up of stigma, style and ovary.
Draw the carpel and label its different parts.
Name the different parts of a stamen.
What are the different parts of a carpel?
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Green Plants
B.
Many flowers have both male and female parts. They are called bisexual flower.
However, flowers of pumpkin, cucumber, maize, etc., contain only male or
female part.
Work in groups
Collect different types of flower from your locality. Observe them carefully and
sort them into the following groups as shown below in Table 9.1. You can use
local or English names.
Table 9.1
Flowers containing only male or
female part.
Flowers containing both male and
female parts.
Share your work with the class.
Write one advantage of a bisexual flower in reproduction.
Check Your Progress
i. Draw a labelled diagram of a flower.
ii. Name three unisexual flowers.
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Green Plants
9.5 Functions of Different Parts of a Flower
Test Yourself
1.
2.
3.
4.
5.
What are the three parts of a carpel?
Draw stamen and label its different parts.
All the sepals together are called _________.
What part of a plant is normally bright in colour?
What is the main function of a flower?
You already know:
parts of a flower.
You will learn:
functions of different parts of a flower.
A. Different parts of a flower carry out different functions.
B.
Which part of the flower is usually brightly coloured? Why?
Which is the outermost part of a flower?
What is the function of sepals?
Bring a flower containing all the parts.
You will use the parts of the same flower for the next activity too. Therefore,
take care of the flower parts.
Work in groups
You will need:
flower
forceps
hand lens
Take the stamen of a flower.
Touch the anther with your finger.
Observe your finger with the hand lens.
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Green Plants
Do you see anything on your finger?
The small particles that you see on your
finger are pollen grains.
Where are pollen grains produced?
What is the function of a filament?
Touch the stigma with your finger.
How does it feel?
Stigma receives pollen grains.
The style is a thin tube that leads from the stigma to ovary. Ovary contains ovules.
What is the function of a style?
Ovary forms fruit and ovules develop into seeds.
Do You Know?
C.
Flower is the seat of
sexual reproduction
and helps in the
formation of seeds
first and then the
development of
fruits.
Work in groups
You will need:
flower parts of activity ‘B’
chart paper
transparent sellotape
forceps
marker pen
rule
Paste different parts of the flower on a chart paper, label the parts and state
their functions. Display it in your class.
Check Your Progress
i. Write the function of anther.
ii. Why is stigma usually sticky?
http://www.familymanagement.com/holidays/flowers/flower_anatomy.html
http://www.tutorvista.com/biology/parts-of-a-plant-for-kids#
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Green Plants
Think Again
1. Match items of column ‘A’ with correct answers of column ‘B’
Column A
Calyx
Carpel
Stigma
Corolla
Stamen
Column B
attracts insects and birds.
male reproductive part of the flower.
female reproductive part of the flower.
protects the inner parts of the flower.
receives pollen grains.
2. List the importance of flowers for human beings.
3. When you cut a stem, a watery liquid may come out. Why?
4. The following are the parts of a flower:
carpel
calyx stamen
corolla
Arrange them in the sequence from outermost to the innermost parts.
5. Write three differences between stem and root.
6. Draw a flower and describe its parts.
7. A weeping willow tree has hard stem from which branches and leaves grow. Its roots
grow long.
What functions of the stem and root does the above sentences describe?
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Chapter 10
Living Things and their Environment
10.1 Food Chains in a Habitat
Test Yourself
1.
2.
3.
4.
5.
Define food chain.
There will be no food chain without plants. Why?
Why are animals called consumers?
Do all animals eat the same food? Why?
Why is it important to have different types of plants and animals
in a habitat?
You already know:
food chain.
consumers and producers.
You will learn:
A.
food chains in a habitat.
Work in pairs
Study the following food chain and answer the questions.
Grass
(Producer)
Grasshopper
(Primary
consumer)
Toad
(Secondary
consumer)
Snake
Hawk
(Tertiary
consumer)
(Quaternary
consumer)
What is a producer?
What does secondary consumer feed on?
What does tertiary consumer feed on?
What is a primary consumer?
Will the food chain be complete without quaternary consumer? Explain.
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Living Things and their Environment
B.
Work in groups
Study the food chain given below in Figure 10.1 and answer the questions that
follow.
Small bird
Butterfly
Flower
Hawk
Figure 10.1
Which one is the secondary consumer in the food chain?
Is hawk a primary consumer? Why?
How is the producer different from the consumers?
C.
Work in groups
Read the following story told by ‘Singee’, the lion and answer the questions that
follow.
Hello everyone!
My name is Singee. People call me lion. I live in the savannah of Africa which is the
largest grassland in the world. It covers about 20% of the Earth’s area.
My family consists of several members. We live in small groups. We belong to a
group of animals resembling cats. We have our cousins, cheetahs and leopards
living in the savannah. All of us are carnivorous.
In the savannah, there is plenty of green grass. Along with the grass, there are
several trees. Some are short while others are tall. Varieties of insects live in the
grass. Many birds find their food from the grass. Trees are home to the birds and
their leaves are the favourite food for elephants and giraffe.
Let me tell you more about life in the savannah. Grass is the favourite food of
zebras, deer, gazelles, wildebeest, wild buffaloes, hippopotamuses and elephants.
We depend for food on some of them. Lots of green grass in our savannah makes
all of us happy and healthy.
Did I tell you about crocodiles and hippopotamus here in the savannah? Well
crocodiles and hippopotamuses spend most of their time in the water. Water here
in the savannah is very important. We all need water to quench our thirst. During
some months of the year, there is water shortage in the savannah. Crocodiles are
carnivorous while hippopotamus are herbivorous. Some animals loose their lives to
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Living Things and their Environment
the crocodiles while drinking water.
Do you have a savannah in your country?
The characters in the savannah make several important food chains.
Write three food chains based on the above story in your notebook. Identify
the producer, primary consumer, secondary consumer, tertiary consumer and
quaternary consumer.
What will happen in the savannah if Singee and his cousin were caught and
taken to a zoo?
Check Your Progress
i. The food chain given below is not in proper sequence. Write in correct
sequence.
Hawk
Frog
Snake
Caterpillar
Plant
ii. Differentiate between primary consumer and secondary consumer.
Savannah
http://e2bn.skoool.co.uk/content/primary/science/food_chains/index.html
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Living Things and their Environment
10.2 What is a Food Web
Test Yourself
1.
2.
3.
4.
5.
Name a primary consumer.
Why is frog a secondary consumer?
What will happen to the snakes if all the frogs were killed?
Why are consumers important in a habitat?
Name some other animals which eat grass.
You already know:
food chain in a habitat.
You will learn:
A.
food web.
In nature, a single food chain does not exist in isolation. All the food chains are
connected, and they intersect each other like the web of a spider. They form a
complete feeding relationship called a food web.
Caterpillar
Bird
Tiger
Deer
Bear
Plants
For example, there are animals other than the caterpillar that eat plants. There
are also animals other than the tiger that eat deer.
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Living Things and their Environment
Study the food web given below in Figure 10.2.
Figure 10.2
From the above food web in Figure 10.2, identify and draw at least three food
B.
chains.
Food Web Game
Select an open space outside the class. Your teacher will help you play this
game.
You will need:
ball of thread
a pair of scissors
name cards (cards should have one of the following names written on it: Plant, Rabbit, Bear, Snake, Tiger, Rat, Deer, Eagle, Wolf, Boar, Lion, Bat.)
Each student should have a name card of one of the above animals hung around
his or her neck.
The game begins with the person carrying plant card, passing the ball of thread
to those with herbivore cards.
Each herbivore then passes the thread to its predator.
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Living Things and their Environment
Remember to link omnivores to the plants.
How many food chains are there in your food web?
What will happen if there are no herbivores?
C.
Work in groups
Read about Jigme Dorji National Park (JDNP).
Jigme Dorji National Park is Bhutan’s second largest protected area of
forest. This national park covers the entire Dzongkhag of Gasa and the
eastern areas of Thimphu and Paro. Black bears, tiger, leopard, wild dog,
marmot, sambar, blue sheep, barking deer, red panda, takin, and musk deer
are found in this area. This may be the only place in the world where the
Royal Bengal Tiger and snow leopard habitats overlap. The park also has
equally rich variety of plants.
JDNP is also the only park in Bhutan where the national animal (takin), the
national flower (blue poppy), the national bird (raven) and, the national
tree (cypress) exist together.
What is a National Park?
What are the special features of JDNP?
Construct five simple food chains that exists in JDNP.
Combine the above food chains and draw a food web.
Check Your Progress
i. What is a food web? Explain with an example.
ii. There are many animals which are harmful to us. However, all animals are
important in a food web. Explain.
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Living Things and their Environment
10.3 Saving Threatened Plants and Animals
Test Yourself
1. Define food web
2. Name at least two preys for the following predators:
a. tiger
b. frog
c. human beings
3. Can we live without plants? Why?
4. Why don’t we see many animals in the forests near cities?
5. What will happen to animals if we destroy their habitat?
You already know:
food web.
You will learn:
A.
threatened plants and animals.
Work in two Groups
Imagine life on Earth without plants and animals.
One group will write about life on Earth without plants. The other group will
write about life on Earth without animals.
Present your work to the class.
Combine the ideas of your group with the other group and write about life on
Earth without plants and animals.
B.
Over millions of years, our Earth has lost varieties of plants and animals. Example,
dinosaurs, woolly mammoth, dodo, passenger pigeon, cry pansy, black Andean
toad and Sri Lanka legume tree.
Black Andean Toad
Dodo
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Dinosaurs
Living Things and their Environment
Passenger Pigeon
Sri Lanka legume tree
Cry Pansy
Woolly mammoth
Work in groups
Carry out a plant and animal status survey in your locality. Interview elders and
find out the following.
Table 10.1
Plants /
Sl No.
Animals
Before
More
Now
Less
More
Less
Reasons for increase/
decrease in number
Write a short report on your findings and present it to the class.
What steps would you take to protect the plants and animals that have decreased
in number?
C.
Animals are important part of our natural resources. They help in maintaining
the balance in nature. If there are no tigers, the number of boar and deer will
increase and they will destroy all the crops.
Similarly, plants help to purify air. If plants are destroyed, herbivores will have
shortage of food. Plants are also important source of medicine.
Following are the list of a few threatened plants and animals of Bhutan.
Asian elephant, golden langur, Bengal tiger, takin, black-necked crane, cordycep
(Yartsa Goenboop), blue poppy, red panda, musk deer, agarwood (agaru),
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Living Things and their Environment
genntiana (pang goen metog), yew (kirang shing), ginseng (bhreeng geera dza).
Yew
(Kirang shing)
Genntiana
(Pang goen meto)
Blue poppy
Asian elephant
Bengal tiger
Musk deer
Golden langur
Red panda
Ginseng
(Bhreeng geera dza)
Agarwood (a-ga-ru)
Black-necked crane
Cordyceps
(Yartsa goenboop)
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Living Things and their Environment
These animals and plants are called threatened or endangered because their
numbers are decreasing. People believe that one day they might disappear from
the Earth.
Go to your school library:
Write about any two threatened plants and animals.
Why do we need to save the threatened plants and animals?
Suggest some ways to save threatened plants and animals.
Check Your Progress
i. Give names of three endangered plants and three endangered animals.
ii. Why do plants and animals become endangered?
Do You Know?
One of the
most important
conservation
organizations is the
World Wide Fund
for Nature (WWF).
Its symbol is a giant
Panda.
http://e2bn.skoool.co.uk/content/keystage3/biology/pc/learningsteps/CORLC/launch.html
http://e2bn.skoool.co.uk/content/keystage3/biology/pc/learningsteps/ADSLC/launch.html
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Living Things and their Environment
10.4 Disappearing Forest
Test Yourself
1. Name some endangered and extinct plants and animals.
2. Why is black-necked crane an endangered species?
3. Why does our government put some restrictions on collecting
cordyceps?
4. List down three importance of forest.
5. What are some of the reasons for disappearing of forests?
You already know:
endangered plants and animals.
You will learn:
disappearing forest.
A. Forest is the major habitat for most of the plants and animals. We must take
special care of them. Forests all over the world are disappearing fast. They are
disappearing for many reasons.
A few reasons are mentioned below.
Money
Forests provide timber for building, paper making and furniture. Many trees
can be cut down quickly using modern machines. The person who sells them
makes lots of money.
What will happen to the animals living in forests if all the trees are cut down?
Shifting cultivation
Forest soil is very fertile. People clear
forest to grow crops. Crops grow quite
well for a few years only, and then people
must clear another area of forest. This
method of farming is called shifting
cultivation (tseri).
Plant roots hold the soil together. Soil is
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Living Things and their Environment
quickly washed away if trees are cut down.
Work in pairs
Discuss the advantages and disadvantages of shifting cultivation and write it in
your book.
New villages
Forests are cut down for new settlement. People use timber from the forest to
build houses. Some farmers burn the areas
for growing new grass shoots to feed their
cattle and build new roads. If there are
more people more houses and roads are
needed.
How does the increase in human population affect forests?
Fuel
People need fuel for cooking as well as to
keep themselves warm. For most people
in Bhutan, firewood is the main fuel. To
get firewood people cut down trees.
Name some alternative sources of fuel?
Animals
Animals like cattle go to forest to graze and
destroy the plants and trees.
How can we prevent cattle from overgrazing
in the forest?
Check Your Progress
i. What are the effects of shifting cultivation?
ii. How does increasing population affect habitat?
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Living Things and their Environment
10.5 Protecting Habitat
Test Yourself
What is a habitat?
Write any three reasons why forests are destroyed.
How does the destruction of habitat make species endangered?
Mention some ways to reduce our dependence on forest for
firewood.
5. What steps will you take to protect forests?
1.
2.
3.
4.
You already know:
You will learn:
A.
threats to the habitat.
different ways of saving habitat.
Plants and animals are important to maintain the balance in the natural
environment. It is important to protect their habitat to prevent them from
becoming endangered and then extinct. Therefore, national parks, sanctuaries,
reserves and wildlife corridors are created to provide natural habitat for plants
and animals.
Work in groups
Discuss the impact on plants and animals if their habitats are destroyed.
List some of the steps taken by our government to protect the habitat.
Present your findings to the class.
B.
Invite the Gewog forest officials or the head of Gewog (Gup) to give a talk on
community forestry. Prepare a list of questions like:
When was community forestry introduced in your locality?
What are the purposes of community forestry?
What are the roles of students in the community forest?
What are the roles of community in the community forest?
From your discussion with the forest officials, write how community forest helps
in saving the habitat.
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Living Things and their Environment
In small groups, design a poster on “Protecting Habitat for Better Future” and
display in your school.
Check Your Progress
i. How does Social Forestry Day help in protecting the habitat of plants and
animals?
ii. Why is it important to protect habitat?
http://e2bn.skoool.co.uk/content/keystage3/biology/pc/learningsteps/HITLC/launch.html
http://e2bn.skoool.co.uk/content/keystage3/biology/pc/learningsteps/STHLC/launch.html
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Living Things and their Environment
Think Again
1. Choose the correct answer.
a. Interconnected food chains are also known as
i. special food chain.
ii. food web.
iii. food resource.
iv. food producer.
b. Among the following animals, which one is extinct?
i. Woolly mammoth.
ii. Asian elephant.
iii. Bengal tiger.
iv. Golden langur.
c. Which one of the following is not an advantage of planting trees?
i. Provides food.
ii. Gives oxygen.
iii. Prevent soil erosion.
iv. Destruction of land.
d. Primary consumers include
i. herbivore only.
ii. carnivore only.
iii. herbivore and omnivore.
iv. omnivore and carnivore.
e. Which one of the following is not an endangered animal of Bhutan?
i. Golden langur.
ii. Red panda.
iii. Takin.
iv. Boar.
2. How does planting of trees prevent soil erosion?
3. Why is it important save forests? Give three reasons.
4. Why is musk deer an endangered animal?
5. Explain how human beings damage the environment.
6. Why do you think a single food chain cannot exist in isolation?
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Living Things and their Environment
Number of animals
120 240 260 280 300
7. Sonam is a biologist at the Jigme Dorji National Park at Punakha. She maintains
the record of mammals in the park. A graph in Figure 10.3 is produced from the
record.
Red Panda
Boar
Deer
1985 1990 1995 2000 2005 2010
Year
Figure 10.3
i.
ii.
What animals are increasing in population?
Which animal is an endangered animal?
131
Chapter 11
Nutrition and Human System
11.1 Food for Health
Test Yourself
1.
2.
3.
4.
5.
What are the three groups of food?
List down the names of all the food that you have eaten.
From your list write the names of food for protection.
Is it important to take all groups of food? Why?
What will happen if we only take the food for activity?
You already know:
food for activity.
food for growth.
food for protection.
You will learn:
different food groups and their functions.
Work in groups
A.
Look at the following pictures in Figure 11.1.
Butter
Wheat
Potato
Cheese
Pulses
Eggs
Rice
Bread
Oil
Milk
Maize
Sugar
Wheat flour
Grapes
Tomatoes
Carrots
Figure 11.1
132
Cabbage
Spinach
Apple
Nutrition and Human System
Classify the above food items into different food groups in Table 11.1 given
below.
Table 11.1
Energy giving
Protective foods
Body building foods
foods
Energy giving foods like rice, bread, wheat, etc. contain carbohydrates.
Other energy giving foods like butter, oil ,etc. contain fats.
Body building foods like milk, pulses, eggs, cheese ,etc. contain protein.
Protective foods like fruits and green leafy vegetables contain minerals and
vitamins. Other food groups also contain some amount of minerals and vitamins.
Cite some more examples of food that contain carbohydrate, protein, vitamins
and minerals.
Fruits and vegetables also contain fibres. They help to remove the digestive waste
out of the body. Other examples of fibre containing foods are corn, half crushed
wheat, flour, brown rice, whole grain cereals, edible peels of fruits, nuts, and
seeds. Cabbage is one vegetable which provides a lot of fibre.
Water also helps us to digest food and to take digestive waste out of the body.
What happens if the major part of your diet is meat?
B.
Work in groups
You will need:
Rice, tomato, cheese, eggs, spinach, maize, bread, carrot, pulses, cabbage,
oil, bean.
Your teacher will mix the food items that you have brought.
Sort them into foods that contain carbohydrate, fats, protein, fibre, vitamins and
minerals.
Milk is a complete food. Give reasons.
Check Your Progress
i. Is fibre good for health? Support your answer with reasons.
ii. Why are beans better for body building than rice?
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Nutrition and Human System
11.2 Eating Habits
Test Yourself
1.
2.
3.
4.
5.
You already know:
Which food gives us lots of energy?
Why should we take food containing fibre?
In what ways is water important for our body?
Which food item would you prefer, potato chips or rice? Why?
What do you think will happen if you keep on eating chips for
a month?
different kinds of food groups
You will learn:
impact of junk food on our health.
A.
Foods are important for our healthy living. They must contain all type of
nutrients needed for growth, protection and work. They must be taken on regular
time. Nowadays, foods are available in many forms, cooked and uncooked.
List down the various packaged food you take. Why do you take these foods?
Are these packaged foods better than the fresh foods?
Food which is unhealthy but is quick, easy and ready to eat is called junk food.
It has very high fat content and little or no nutrients. Some harmful colours and
preservatives are added for better storage and to make the food look attractive.
People eat junk foods at odd hours. This reduces appetite and if less or no normal
food is eaten it may lead to malnourishment. If normal meal is taken after eating
junk food, people can get fat. Junk foods or fast foods contain more salt and fat
than the body needs. Too much fat in the body leads to obesity that can cause
heart problems and other diseases. Besides causing health problems, it’s hamper
also litters our environment if not disposed properly.
B. Nado and Zangmo are brother and sister. Their mother is sick. She asked them
to manage their own food.
This is how they managed their meals.
Breakfast: Nothing. They were already late for school.
Recess (Interval): Two packets of potato chips and cold drinks from school
canteen.
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Nutrition and Human System
Lunch: Two packets of instant noodles and cold drinks.
After school: Some biscuits.
Dinner: Their father ordered momo and tea.
Is the food eaten by Nado and Zangmo, healthy? Why?
Suggest the type of foods Nado and Zangmo should eat during breakfast, lunch
and dinner to keep themselves healthy.
C.
Work in groups
Go around your school campus and collect plastic covers and bottles.
Where do you think these plastic covers and bottles come from?
Plastics and bottles take many years to decay.
What type of waste is it?
What should you do with those litters?
Is it good to burn plastics and bottles? Why?
Check Your Progress
i. Make a list of junk foods.
ii. Why should we avoid junk foods?
http://e2bn.skoool.co.uk/content/primary/science/healthy_eating/index.html
135
Nutrition and Human System
11.3 Human Transport System
Test Yourself
1.
2.
3.
4.
5.
You already know:
Give three examples of junk food
Junk food is bad for our health. Why do you think so?
Name some of the most important parts of our body.
What do you observe when a part of your body gets injured?
What happens to your heart beat when you run faster?
junk food causes heart problems.
You will learn:
organs in our body.
heart, blood vessels and their functions.
A. Our body is made of organs. An organ is a part of the body which does special
work. Heart and lungs are examples of organs.
Put your hand on the left side of your chest. You will feel the beating of the heart.
The heart is about the size of your fist. The heart pumps blood around your
body.
Do You Know?
Our heart beats
about 100,000
times a day.
Feel your ribs. Your lungs fit inside your ribs. Ribs protect your heart and lungs.
Your heart is between your lungs. Lungs are for breathing.
136
Nutrition and Human System
B.
Heart pumps blood through pipes called blood vessels. There are two kinds
of blood vessels: arteries and veins. Arteries take blood away from the heart.
For example, pulmonary artery and aorta take blood away from the heart to
different parts of the body. Veins bring blood back to the heart. For example,
pulmonary vein and vena cava bring blood from different parts of the body back
to the heart.
Blood supplies the digested food and oxygen and collects waste from different
parts of the body.
Heart, blood and blood vessels form the human transport system.
Figure 11.2
Copy and complete the following Table 11.2.
Figure 11.2
Parts
Functions
Heart
Blood
Blood Vessels
Check Your Progress
i. Which organ in our body is like a pumping machine?
ii. Name the two types of blood vessels.
137
Nutrition and Human System
11.4 Skeleton and Muscle
Test Yourself
1.
2.
3.
4.
5.
Define organ.
What are the three parts of human transport system?
Name the organ which pumps blood in our body.
What gives shape to our body?
What do you think will be the functions of bones and muscles in
our body?
You already know:
heart and blood vessels.
You will learn:
skeleton and its functions.
muscle and its functions .
A.
What holds you up?
A collection of bones that holds a body together is called skeleton. A skeleton
supports a body. Bones are of different sizes and shapes because they carry out
different functions. Some animals like cat, dog, tiger, snake, bird, fish, etc. also
have skeleton.
Skeleton also gives shape to the body. Without it the body would be like a piece
of jelly.
Skull
Collar bone
Shoulder blade
Breast bone
Rib cage
Arm bone
Back bone
Hip bone
Thigh bone
Fingers
Knee cap
Leg bone
Toes
Figure 11.3
138
Nutrition and Human System
Which bone do you find in the centre of the chest?
Which bone provides shape to the head?
Write the names of bones that help in walking.
B. Let your arm hang down. Feel your upper arm. Now bring the lower arm towards
the upper arm. Feel the muscles with the other hand.
Can you name some other parts of your body where muscles are present?
Muscles are attached to skeleton in our body. Muscles and skeleton give shape,
protection, and help in movement.
Neck muscles
Shoulder muscles
Triceps
Biceps
Abdominal muscles
Thigh muscles
Calf muscles
Shin muscles
Figure 11.4
Name the muscles which help in lifting a book
Let us make a model to see how the muscles work.
Work in pairs
Bone
You will need:
a pair of scissors
cardboard
elastic bands
drawing pins
Biceps
Bone
Pin
Cut the cardboard into the shape of Triceps
two bones that are shown in Figure
11.5.
139
Pin
Figure 11.5
Nutrition and Human System
Fix the cardboard as shown in Figure 11.5.
Attach the elastic bands to the bones with the
help of pins.
The elastic bands represent the muscles in our
arm.
Make the bones and muscles move.
Which muscle is stretched when the arm
moves up?
Do You Know?
A new-born baby has
more than 300 bones.
As the baby grows older,
some bones join together.
An adult human has
206 bones and over 600
muscles in the body.
C. To make our muscles strong we need plenty of
body building food.
Name some body building foods.
Exercise is good for our muscles.
Farmers get a lot of exercise.
If you work at a desk for most of the day, you can play games to get exercise.
Work in groups
Discuss and write the muscles that are used while playing the games shown in
the pictures in Figure 11.6 given below?
Figure 11.6
Share your answers with the class.
Check Your Progress
i. Make a list of junk foods.
ii. Why should we avoid junk foods?.
140
Nutrition and Human System
Think Again
1. Fill in the blanks with correct words.
a. Carbohydrates give us ______________.
b. ___________ carry blood from the heart to all parts of the body.
c. Our bones are moved by ________________.
d. Proteins are needed for __________________.
e. ___________ and ___________ protect the heart and the lungs.
2. Eating junk food makes people malnourished. Why?
3. What are the main functions of our skeleton?
4. Which of the following contain fibre: Milk, orange, sausages, bread, butter, egg,
rice, spinach?
5. What are the main functions of our muscles?
6. Explain the circulatory system using the following terms: Heart, blood, blood
vessels, arteries, veins, food, oxygen.
7. An earthworm can wriggle around and move through the tiny holes in the
ground. But can not stand like the dog or a cat. Give reasons.
http://e2bn.skoool.co.uk/content/keystage4/biology/pc/lessons/uk_ks4_blood_and_circulation/
h-frame-ns6.htm
http://www.abcya.com/skeletal_system.htm
http://www.playkidsgames.com/games/wordFind/Skeletal%20System/default.htm
141
Chapter 12
Our Moon
12.1 The Moon
Test Yourself
1.
2.
3.
4.
You already know:
Earth is the planet on which we live.
You will learn:
A.
What are the effects of rotation and revolution of the Earth?
What makes Earth favourable for all living things to live in it?
How many moons does the Earth have?
Why do we see moon in different shapes?
the Moon.
The moon is our nearest neighbour in space. It is smaller than the Earth. It is
the Earth’s natural satellite. Heavenly bodies which move around the planets are
called natural satellites. The objects which are placed into orbit in the space by
human beings are called artificial satellites. From your school library, find out
some of the uses of artificial satellites.
Moon has no light of its own. It gets light from the sun. This light is reflected to
the Earth as moonlight.
The moon takes about a month to revolve around the Earth. It also takes about
the same time to complete one rotation. This is why the same side of the moon
always faces us.
Work in groups
Note book
You will need:
mirror
notebook
Torch
Mirror
Figure 12.1
142
Our Moon
torch
curtains
Make your classroom dark.
Light the torch on the mirror.
Adjust the mirror till the light from the mirror falls on the notebook as shown
in Figure 12.1.
How does the light reach the notebook?
Does the mirror give out its own light?
In what way does the mirror represent the moon?
In what way does the torch represent the sun?
Do not carry out the
experiment with broken
mirror. It might injure you.
B. The shape of the moon appears to change continuously.
The moon waxes (lit up portion increases in size) and wanes (lit up portion
decreases in size) as it moves around the Earth. This waxing and waning of the
moon is called phases of the moon.
The change in the shape of the moon is due to the change in position of the
moon with respect to Earth.
Phases of the moon are shown in Table 12.1 below.
Table 12.1
Lunar week
Phase of the moon
1st week
Phase 1 (New moon) and Phase 2 (Waxing crescent)
2nd week
Phase 3 (First quarter) and Phase 4 (Waxing gibbous)
3rd week
Phase 5 (Full moon) and Phase 6 (Waning gibbous)
4th week
Phase 7 (Last quarter) and Phase 8 (Waning crescent)
Making lunar calendar.
Your teacher will provide you a copy of this calendar.
Your observations should start from the first day of lunar (Bhutanese) calendar.
Draw the appearance of moon every night.
In case of cloudy nights leave the drawing blank.
143
Our Moon
༡
༢
༣
༤
༥
༦
༧
༨
༩
༡༠
༡༡
༡༢
༡༣
༡༤
༡5
༡6
༡7
༡8
༡9
20
21
༢2
༢3
༢4
༢5
༢6
༢7
༢8
༢9
30
Show this calendar to the teacher every week.
Compare your observations with that of your classmates.
Predict what will happen to the moon in the next week?
Check Your Progress
i. What are satellites?
ii. What are some of the uses of artificial satellites?
http://e2bn.skoool.co.uk/content/keystage3/Physics/pc/learningsteps/STLLC/launch.html
144
Our Moon
12.2 Moon in the First Week
Test Yourself
1.
2.
3.
4.
You already know:
moon is a satellite.
You will learn:
A.
Name the natural satellite of the Earth.
Does moon have its own light?
Moon appears to change its shape all the time. Why?
Why is the moon not visible on new moon phase?
moon in the first week.
When the moon is in between the Sun and the Earth, the side that faces the
Earth does not get any sunlight. So it is completely dark. This is called new
moon (Nam-gang).
After a new moon, the moon revolves around the Earth changing its position. A
very small part of the moon is visible from the Earth. This small visible part is
called waxing crescent moon [Yar-ngo daw].
Work in pairs
You will need:
a pair of scissors
paper
black crayon
New moon
Waxing crescent moon
Draw two phases of first lunar week on a sheet of paper. Cut and keep it for the
next activity.
Check Your Progress
i. Name the two phases of the first lunar week.
145
Our Moon
12.3 Moon in the Second Week
Test Yourself
1.
2.
3.
4.
You already know:
moon in the first week.
You will learn:
A.
What is new moon?
Does moon produce heat and light like sun?
Define waxing crescent moon.
Predict the phases of the moon in the second week.
moon in the second week.
When the moon is in the first quarter of its phase, half of the moon is illuminated
by the sunlight. It appears as half moon. This is the first quarter of the moon.
After the first quarter, more than half of the moon is visible. This phase of moon
is called waxing gibbous [Yar-ngo daw].
Work in pairs
You will need:
a pair of scissors
paper
Draw the two phases of second lunar
week on a sheet of paper. Cut and keep
it.
First quarter
Check Your Progress
i. Name the two phases of the second lunar week.
146
Waxing gibbous
Our Moon
12.4 Moon in the Third Week
Test Yourself
1.
2.
3.
4.
You already know:
moon in the second week.
You will learn:
A.
Draw the phases of the moon in the second week.
What is waxing gibbous?
Why is the moon fully visible on a full moon night?
Predict the phases of the moon for the third week.
moon in the third week.
Two weeks after the new moon, the moon reaches the opposite side of the Earth.
We see the full moon (ChoNga Dawa).
After the full moon, the lit portion of the moon decreases. The moon is now said
to be waning gibbous.
You will need:
a pair of scissors
paper
Draw two phases of third lunar week
on a sheet of paper. Cut and keep it.
Full moon
Check Your Progress
i. Name the two phases of the third lunar week.
147
Waning Gibbous
Our Moon
12.5 Moon in the Fourth Week
Test Yourself
1.
2.
3.
4.
You already know:
moon in the third week.
You will learn:
A.
What is a full moon?
Draw the phases of the moon in the third week.
Whatisthedifferencebetweenthefullmoonand the newmoonphases?
Predict the phases of the moon for the fourth week.
moon in the fourth week.
The moon continues waning until it reaches its last quarter. The one fourth of
the moon is left illuminated. The moon at this phase is known as last quarter.
After the last quarter of the moon’s phase, the size of the illuminated side of the
moon continues to decrease. This phase is called waning crescent. It ends with
a new moon, when the phases begin again. This cycle takes about 29.5 days.
Last quarter
Waning crescent
New moon
Work in pairs
You will need:
a pair of scissors
paper
Draw two phases of fourth lunar week on a sheet of paper. Cut and keep it.
148
Our Moon
B.
Work in pairs
You will need:
chart paper
compass
a pair of scissors
thumb pins
Window
Moon phases wheel
Wheel 1
Wheel 2
Figure 12.2
Draw Wheel 1 and Wheel 2 on a chart paper of radius 10 cm each.
Cut out Wheel 1 and Wheel 2 as shown in the Figure 12.2.
In Wheel 1, cut a cone shaped window to fit two phases of the moon.
Paste all the cut out phases of the moon from activities 12.2 to 12.5 A on wheel 2.
Place Wheel 1 on top of Wheel 2.
Attach the two wheels with thumb pin at the centre.
Now, rotate only Wheel 1 and observe the lunar weeks.
Display your work in the class.
How many phases of the moon did you
observe in one complete rotation of
Wheel 1?
C.
Work in pairs
3
2
1
Table
4
5
Torch
Ball
You will need:
football
6
8
newsprint paper
torch
7
Cover the ball with a newsprint paper.
Figure 12.3
Keep it at the centre of a table as shown in Figure 12.3.
149
Our Moon
Make the room dark.
Stand opposite to your friend.
Ask your friend to light the torch on the ball.
Make sure your friend does not move.
What do you see?
Now you move to next position as shown in the diagram.
What do you see?
Observe the changes of the lit portion of the ball from all the positions.
Which phase of the moon does each position represent?
Check Your Progress
i. Name the two phases of the fourth lunar week.
ii. What will happen if the moon has its own light?
http://e2bn.skoool.co.uk/content/primary/science/earth_and_beyond/index.html
150
Our Moon
Think Again
1. Fill in the blanks.
a.
________ is the Earth’s natural satellite.
b. The moon takes about one ___ to complete one revolution around the Earth.
2.
c.
Changing shapes of the moon are called ____________ of the moon.
d.
When the moon is not visible at all, it is known as ___________ moon.
e.
Moon receives light from the _____________
What will happen if the moon does not revolve around the earth??
3. How many weeks does the moon take to reach from first quarter to last quarter?
4. Arrange the phases of the moon in the correct order.
waning gibbous, new moon, last quarter, waxing gibbous, full moon,
waxing crescent, waning crescent, first quarter.
5. Imagine and write a paragraph about life on Earth if there are two moons.
6. We can not see the moon on a cloudy night. This indicates that they are at
different distances from the Earth. Of the two, cloud and moon, which one is
the farthest from the Earth?
7. Name phases of moon given in Figure 12.4 and Figure 12.5.
Figure 12.4
Figure 12.5
151
Annexure - A
2
2
3
1.2.Change of State
SAQ
(1)
1.3.Properties of Solids
1.4.Properties of Liquids
1.5.Floating Liquids
SAQ
(1)
MCQ
SAQ
(1)
2items- 2marks
1 item- 1 mark
1 item- 1 mark
ERQ
(2)
2
1
MCQ
3
2.3.Dissolving A physical Change
2.4.Melting and Freezing Physical Change
2.5.Are Boiling and Evaporation Physical
Changes
FB
MCQ
1
FB
1
3.3.Separating by Sieving
3.4.Separating by Winnowing
8
1 item- 1 mark
2
3
1 item- 2marks
1
8
1 item- 1 mark
1 item- 2 marks
TF
MCQ
2 items- 2marks
1 item- 1 mark
MCQ
ERQ
(2)
1
1
2
1 item- 2 marks
1
1
TF
SAQ
(1)
4.2.Frictions in Everyday Life
FB
MCQ
MCQ
5. Light and Sound
1
5.1.What Makes White
Mat
FB
2
3
2
MCQ
SAQ
(2)
5.2.Bouncing Light
5.3.Musical Sound
MCQ
Mat
1
3
SAQ
(2)
6.1. How we generate Electricity
6.2. Connection in Series
152
Mat
2
1 item- 1mark
9
2 items- 2
marks
1 item- 2 marks
1 item- 1mark
ERQ
(2)
5.4.How Sound Differs
5.5.Making Music
6
1 item- 1 mark
2 items-2 marks
2 items- 2marks
Mat
1
1 item- 2marks
1 item- 1 mark
2 items- 2 marks
TF
ERQ
(2)
3.5.Magnets as Separators
6. Electricity and Magnetism
2
SAQ
(2)
3.2.Separating by Hand Picking
4.3.Increasing Friction
4.4.Decreasing Friction
1 item- 2 marks
SAQ
(2)
2.2.What are Physical Changes
4. Frictional Force
4.1.Force that Oppose
2 items- 2marks
MCQ
1.6.Properties of Gas
3. Separating Solid Mixtures
3.1.Types of Solid Mixtures
9
1 item- 1 mark
TF
2. Physical Change
2.1.Natural and Man-made Changes
Total
Evaluation/ Evaluate
1
2
FB
Synthesis/ Create
Analysis/ Analyse
1. Matter
1.1.What are Elements
Application/ Apply
Chapter/content
Comprehension/
Understand
Objectives/skills
Knowledge/ Remember
Test Blue Print
1
1 item- 2 marks
2 items- 2 marks
2
9
1 item- 2 marks
ERQ
(2)
1 item- 2marks
6.3. Static Electricity
MCQ
6.4. Which part of magnet is strong
MCQ
6.5.Like and Unlike Poles
FB
7. Energy
7.1.What is Energy
7.2.Different Forms of Energy
7.3.Saving Energy
7.4.Things that Save Energy
1
MCQ
TF
Mat
Mat
1
2
1
1
FB
Mat
Mat
2
SAQ
(2)
1
TF
2
2
1
2
8.3.Difference Between Plants and
Animals
8.4.Individuals are Different
1 item- 1 mark
SAQ
(2)
FB
1
1 item- 2 marks
MCQ
1
MCQ
2
1
2 items- 2 marks
2
TF
MCQ
MCQ
SAQ
(2)
9.5.Functions of different Parts of a Flower
1
2
3
1
10.1.Food Chains in a Habitat
FB
10.4. Disappering Forests
10.5. Protecting Habitat
TF
11. Nutrition and Human System
3
MCQ
12. Our Moon
4
12.1.The Moon
12.2. Moon in the First Week
12.3. Moon in the Second Week
2
SAQ
(2)
1 item- 2 marks
1 item- 1 mark
2 items- 2 marks
MCQ
4
1
ERQ
(2)
Mat
8
2 items- 2
marks
1 item- 2 marks
Mat
1 item- 2marks
1 item- 2 marks
2
SAQ
(2)
1
8
1 item- 2 marks
MCQ
10
marks
9
1 item- 2marks
1 item- 1mark
SAQ
(1)
12.4. Moon in the Third Week
12.5. Moon in the Fourth Week
1 items- 2 marks
2 item- 2marks
SAQ (2)
1
9
2 item- 2 marks
2 items- 2marks
1 item- 1mark
1 item- 2 marks
TF
11.2. Eating Habits
11.3. Human Transport System
11.4. Skeleton and Music
ERQ
(2)
MCQ
ERQ
(2)
MCQ
10.3.Saving threatened Plants and Animals
11.1. Food for Health
2
FB
9.4.Parts of a Flower
10.2.What is Food Web
9
1 item- 1 mark
1 item- 1mark
MCQ
8.6.Life Cycles of Some Animals
1 item- 2 marks
1 item- 2marks
SAQ
(1)
8.5.Variation in Plants and Animals
10. Living Things and Their Environment
1
ERQ
(2)
8.2.Plant Characteristics
9. Green Plants
9.1.Parts of Plants
9.2.Functions of Root
9.3.Functions of Stem
8
1 item- 1 mark
1 item- 2marks
2 items- 2marks
1 item- 1 marks
MCQ
7.5.Energy Change
8. Characteristics of Living Things
8.1.Animal Characteristics
1 item- 1mark
2 items- 2
marks
2 items- 2 marks
1 items- 1marks
MCQ
ERQ (2)
17
marks
22
marks
MCQ
19
marks
1 item- 1 mark
2 items- 3marks
18
marks
14
marks
100 Marks
Note: The number given in the brackets is the marks intended for each question. Item refers to the questions.
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Type of questions
1.
2.
3.
4.
5.
6.
Types of questions
Multiple Choice Questions (MCQ)
Fill in the Blanks (FB)
Match the Following (Mat)
True and False (TF)
Short Answer Questions (SAQ)
Extended Response Questions (ERQ)
Items
25 items
10 items
10 items
10 items
14 items
10 items
154
Marks
25 marks
10 marks
10 marks
10 marks
25 marks
20 marks
Annexure - B
Model Question Paper
Subject: Science
Full Marks: 100
Class: V
Time: 2 Hrs
------------------------------------------------------------------------------------------------------------------------------Question 1
Direction: Each question is followed by four possible answers. Choose the correct answer and write it
down in your answer sheet. (25 Marks)
1. Table is a solid because it has
a. no space and volume.
b. definite shape and volume.
c. definite shape and volume .
d. fix volume but no shape.
Answer: b. definite shape and volume.
2. The following liquids float on water EXCEPT
a. kerosene.
b. mustard oil.
c. soya oil.
d. honey.
Answer: d. honey.
3. The following are man-made changes EXCEPT
a. changing weather.
b. cooking food.
c. burning wood.
d. constructing road.
Answer: a. change in weather.
4. Which sequence represents the order of lifecycle of many plants?
a. seed develops inside fruit → seed is dispersed → seed germinates → plant grows
b. seed is dispersed → seed develops inside fruit → seed germinates → plant grows
c. seed germinates → plant grows → seed is dispersed → seed develops inside fruit
d. seed is dispersed → plant grows → seed germinates → seed develops inside fruit
Answer: a. seed develops inside fruit → seed is dispersed → seed germinates → plant grows
5. Sand and pebbles can be separated by
a. sieving.
b. filtration.
c. decantation.
d. sedimentation.
Answer: a. sieving.
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6. Winnowing is a processes of separating
a. soluble and insoluble substance..
b. light and heavy objects.
c. big and small objects.
d. magnetic and non magnetic.
Answer: b. light and heavy objects.
7. We add oil to rusted things to
a. increase friction.
b. increase weight.
c. decrease friction.
d. decrease weight.
Answer: c. decrease friction.
8. The sunlight composes of seven colours and they are
a. violet, indigo, blue, green, yellow, pink and red.
b. violet, indigo, black, green, yellow, orange and red.
c. violet, indigo, blue, green, yellow, orange and red.
d. violet, indigo, brown, green, yellow, orange and red.
Answer: c. violet, indigo, blue, green, yellow, orange and red.
9. The sharpness of the musical sound can be increased by
a. increasing the length of the string.
b. decreasing the length of the string.
c. decreasing the tension of the string.
d. increasing the thickness of string.
Answer: b. decreasing the length of the string.
10. Static electricity is also known as
a. frictional electricity.
b. hydro electricity.
c. wind electricity.
d. thunder and lightning electricity.
Answer: a. frictional electricity.
11. The ends of a magnet are called North Pole and South Pole because
a. they always point at the North Pole and South Pole.
b. they are the strongest part of a magnetic.
c. they never point at the Earth’s Poles.
d. they are the only poles in a magnet.
Answer: a. they always point at the North Pole and South Pole.
12. The unit of energy is
a.
b.
c.
d.
kilograms.
newton.
joule.
metre.
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Answer: c. joule.
13. Which of the following are appliances that save energy?
I. Pressure cooker.
II. Compact florescent lamp.
III. Bicycle.
IV. Car.
a. I,II and III.
b. I,II and IV.
c. II,III and IV.
d. I,III and IV.
Answer: a. I, II and III.
14. Variation in living things is the
a. differences among individuals belonging to the same group.
b. differences among different groups.
c. similarities among individuals belonging to the same group.
d. similarities among individuals belonging to the different group.
Answer: a. differences among individuals belonging to the same group.
15. Water is an example of compound. The diagram shows a molecule of water. How many element(s)
does it contain?
a. Four.
b. Two.
c. One.
d. Three.
Answer: b. Two.
16. Fertilization is the process of
a. producing new ones.
b. fusion of ovum and sperm.
c. beginning life.
d. ending life.
Answer: b. fusion of ovum and sperm.
17. The function of the roots is to
I. hold the plant in the soil.
II. absorb water.
III. absorb minerals.
IV. make food.
a. I and II.
b. I,II and III.
c. I,II and IV.
d. I and III.
Answer: I, II and III.
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18. The function of the stem is to
I. holds leaves and flowers.
II. conducts water and minerals to the leaves.
III. absorbs water.
IV. makes food.
a. I and II.
b. II and III.
c. III and IV.
d. I and IV.
Answer: a. I and II.
19. The producer is more than the consumer so that the
a. food is sufficient.
b. number of producer increases.
c. number consumers increases.
d. number of producers decreases
Answer: a. food is sufficient.
20. The shifting cultivation will result in
I. soil erosion.
II. afforestation.
III. better harvest.
IV. global warming.
a. I and II.
b. II and III.
c. I and III.
d. I and IV.
Answer: d. I and IV.
21. We can protect habitat by
a. shifting cultivation.
b. deforestation.
c. hunting.
d. creating national parks.
Answer: d. creating national parks
22. An example of a complete food is ................................ .
a. egg.
b. butter.
c. rice.
d. milk.
Answer: d. milk.
23.Which type of energy in petrol is transformed into mechanical energy in a motorcycle engine?
a. Chemical.
b. Magnetic.
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c. Nuclear.
d. Electrical.
Answer: a. Chemical.
24. The diagram below shows a baby elephant with its mother.
The baby elephant’s trunk is an example of
a. a response to the environment.
b. an inherited trait.
c. coloration to attract mates.
d. a seasonal adaptation.
Answer: b. an inherited trait.
25. Which behavior will best help a student stay healthy?
a. watching television five hours a day.
b. sleeping three hours each night.
c. eating fruits and vegetables each day.
d. exercising once a month.
Answer: c. eating fruits and vegetables each day.
Question 2
Direction: Fill in the blanks. Write only the answer against the number in the answer sheet. (1x10)
1. A matter which is made up of only one kind of particle is called…………………
Answer: an element
2. …………….is a process in which a substance disappears in a liquid.
Answer: Dissolving
3. Mixture of iron fillings and sand is ………. mixture.
Answer: solid-solid
4. The combination of violet, indigo, blue, green, yellow, orange and red make up a................................
Answer: spectrum.
5. The North seeking pole of a magnet is called… …………
Answer: North Pole.
6. The energy of an object raised to a height is ………………energy.
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Answer: potential
7. The process of an animal or a plant beginning life, growing and reproducing is called a ……………
Answer: lifecycle.
8. The part of a plant above the ground is called.............................
Answer: shoot.
9. The intersection of food chains is called…………….
Answer: food web.
10.The waning and waxing of moon is called ………..
Answers: phases of moon.
Question 3
Direction: Match the following. Write only the alphabet against the number in your answer sheet.
(10 Marks)
Answer:
Column A
Column B
Answers
1. Veins
a. fresh blood
f
b. consumes lot of energy
2. Arteries
a
h
3. Treads
c. iron filling
4. Oil
d. saves energy
j
e. conch
g
5. Percussion instruments
6. Wind instruments
f. used blood
e
g. drum
c
7. Magnetic
8. Like poles
h. increase friction
i
9. Compact florescent lamp
i. repel
d
10.Incandescent bulb
j. decrease friction
b
Question 4
Direction: Write True or False against the number in your answer sheet. (10 Marks)
1. When a substance is melted, its mass the same while its shape changes.
Answer: True.
2. Melting and freezing are not physical change.
Answer: False
3. We can separate solids having same size by sieving.
Answer: False
4. We slip on a wet floor because there is less friction.
Answer: True
5. The roots make food for the plant.
Answer: False
6. The energy stored in food and fuel is called kinetic energy.
Answer: False
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7. Characteristics are unique features by which we describe about animals and plants.
Answer: True
8. It is important to protect habitat to maintain balance in nature.
Answer: True
9. Fibre helps in removing digestive wastes from our body.
Answer: True
10.The increase in the lit up portion of moon is called waning.
Answer: False
Question 5:
Direction: Answer the following question as directed. All answer must be written in your answer sheet.
The marks are given in the bracket for each question. (25 Marks)
1. Why is a chair an example of solid? (1)
Answer: Because it has definite shape and volume.
2. Study the following experiment and answer the questions given below.
Cotton
Inverted funnel
Crystals of Ammonium chloride
Heat
i. What process do you observe in the above experiment? (1)
Answer: On heating the ammonium chloride undergoes the process of sublimation.
ii.
What change is it? Why? (1)
Answer: It is a physical change because no new substance is formed and we can get back the original
substance.
3. What is physical change? Give two examples. (2)
Answer: A change in which no new substances are formed. For example, melting of an ice and heating of
water
4. When is hand picking an effective method of separation? (2)
Answer: When the solids are of different colour, size and shape.
5. State one situation where friction is important in everyday life. (1)
Answer: Friction helps us to walk.
6. Why is our reflection not clear on a frosted glass? (2)
Answer: Because it has uneven surface and the light is reflected in all direction.
7. Explain how electricity is produced in hydropower stations. (2)
Answer: The water from the dam flows through a tunnel. The water turns the turbine, which turns the
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generator, thus completing the energy conversion from potential energy of the water to kinetic
energy of the turbine and to electrical energy (electricity).
8. Write the energy chain that occurs when you ring an electric bell. (2)
Answer : Electric energy
kinetic energy
sound energy
9. How do variations help animals? (2)
Answer: It helps animals to adapt and protect themselves from predators to survive.
10.Which part of the flower is usually sticky? Why? (2)
Answer: Stigma is usually sticky so that the pollen grain sticks to it for fertilization to take place.
11.Make a food chain of 4 consumers.(2)
Answer: Dragonfly
frog
snake
hawk
12.Label the following diagram. (2)
Answer:
skull
Shoulder blade
Rib cage
Knee cap
13.Why do we see the moon in different shape?(1)
Answer: Because the moon waxes and wanes as it moves around the Earth due to the position of the
moon with respect to Earth.
14.Explain why children should avoid junk food. (2)
Answer: The junk foods are easy to prepare but they do not contain all the nutrients required by the growing
body of a child. Dependence on the junk food can lead to malnutrition and the body can become
obese.
Question 6:
Direction: Answer the following questions as directed in your answer sheet. (20 Marks)
1. Gas does not have fixed shape and volume. Why? (2)
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Answer: Because the particles are far apart and the particles are free to move in all directions.
2. Why do dogs stick out their tongues in a hot weather? (2)
Answer: Dogs stick out their tongues to cool their bodies through the process of evaporation from the
tongues.
3. Why can’t we separate rice and husks using a magnet? (2)
Answer: Because they are not magnetic substances.
4. If you are to play music in an open air what would you do to make the music loud? Why? (2)
Answer: Use a big sound box as, bigger the sound box louder the sound.
5. Draw an open circuit and label it.(2)
Dry cell
Answer:
Switch
Bulb
6. Name the different phases of the moon in the following diagrams. (2)
1 2 3
6 7
4
5 8
9
Answer:
1. Full moon
6. Waxing gibbous
2. Waning Gibbous
7. Last quarter
3. New moon
8. Waning Gibbous
4. Waxing crescent moon
9. New moon
5. First quarter
7. The diagram below shows water boiling in a metal pan on a burning gas stove.
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Explain why the handle of the pan is made of wood. [1]
Answer: It is because wood is a bad conductor of heat. So the heat from the pan will not burn our hands.
8. Read the following and answer the questions that follow.
Benjamin Franklin was the first scientist to discover static electricity. This electricity does not use
circuit to flow. It is produced by rubbing the two objects against each other. While rubbing, the friction
produces positive and negative charges. Like charges repels and unlike charges attract. For example,
rubbing of inflated balloons against wool will charge the balloons with negative charges and wool with
positive charge. If we bring charged balloons together, they will repel each other as they have like
charges. If we take the charged balloons to the wall, they stick on the wall as unlike charges attract.
On the stormy day, clouds collide with each other creating massive charges which we see as lightning.
i. What causes lightning on a stormy day? (1)
Answer: The collision of clouds in the atmosphere produces the lightning.
ii. What is the type of electricity you see on the sweater on a dry day night? (1)
Answer: The electrostatic electricity is observed on the sweater on the dry day night. We do not see this on
the wet day night.
9. The mask deer is one of the endangered animal species in Bhutan. Why? What can we do to protect the
endangered plants and animals? (2)
Answer: The mask deer is wanted for its bile which has medicinal values, so it is hunted by many people.
Owing to this, the number of mask deer is declining very fast and a day will come when there will
be no mask deer in the forest. To put check on the habit of people hunting for mask deer, we need to
develop protected areas, stop hunting by providing alternative means of income, and reduce over
harvesting of any endangered natural resources.
10. Draw and label the parts of a flower.(3)
Stigma
Answer:
Anther
Style
Ovary
Stamen
Petal
Filament
Sepal
Pedicel
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