STARTING(TheALL
OVER
AGAIN
Cycles of Nature)
GRADES 6 - 8
written by
Lois Andre Bechely
KarenBeth Traiger
for the
California Foundation for Agriculture in the Classroom
in cooperation with the
California Department of Education
California Department of Food and Agriculture
California Farm Bureau Federation
Fertilizer Inspection Advisory Board
Fertilizer Research and Education Program
Illustrators
Karin Bakotich
Lois Andre Bechely
Sherri Freeman
Regina Johnson
Editors
Margaret Anderson
Pamela Emery
Carolyn McClelland
Agriculture In The Classroom
1601 Exposition Boulevard
Sacramento, CA 95815
(916) 924-4380
September, 1994
TABLE OF CONTENTS
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
.. 5
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..........
Unit Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Lessons:
All Aboard the Carousel (A lesson on Cycles) ..................................................................... 8
Read All About It! (A Cycles Reading Assignment) ............................................................ 11
The Rotting World (A Decomposition Experiment).......................................................... 26
Around and Around Nitrogen Goes! (A Nitrogen Cycle Game)........................................... 33
Play It Again, Nitrogen! (A Nitrogen Cycle Role-play) ................................................... 4 0
Educational Resources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 8
. . 50
Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ...............
. . 52
Footnotes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..............
ACKNOWLEDGMENTS
This unit was funded by a grant from the Fertilizer Research and Education Program, the
California Foundation for Agriculture in the Classroom, the California Department of Food and
Agriculture, the Fertilizer Inspection Advisory Board and the California Farm Bureau
Federation.
The Fertilizer Research and Education Program provides funding to conduct research and
education projects directed toward the environmentally safe and agronomically sound use and
handling of fertilizer materials.
The California Foundation for Agriculture in the Classroom is dedicated to fostering a greater
public knowledge of the agricultural industry and seeks to enlighten students, educators, and
leaders in the public and private sector about agriculture’s vital, yet sometimes forgotten, role
in American society and the effect all citizens have on agriculture’s well being.
We would like to thank the following people who helped create, write, revise and edit this unit.
Their comments and recommendations contributed significantly to the development of this unit.
However, their participation does not necessarily imply endorsement of all statements in the
document.
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Writers
Editors
Pilot Testers
Lois Andre Becheiy
Educational Consultant/Former
Teacher
Los Angeles Unified School
District
Los Angeles, CA
Margaret Anderson
Communications Consultant
Birds Landing, CA
J e r r y Delsol
Middle School Agriscience
Teacher
Douglass Junior High School
Woodland Joint Unified School
District
Woodland, CA
KarenBeth T r a i g e r
Elementary Science Teacher
Graystone Elementary School
San Jose Unified School District
San Jose, CA
Pamela Emery
Curriculum Coordinator
California Foundation for
Agriculture in the Classroom
Sacramento, CA
Carolyn McClelland
English Teacher
Dover Middle School
Fairfield-Suisun Unified School
District
Fairfield, CA
KarenBeth T r a i g e r
Elementary Science Teacher
Graystone Elementary School
San Jose Unified School District
San Jose, CA
Pam Mossman
Fourth Grade Teacher
Sandrini Elementary School
Panama-Buena Vista Union
School District
Bakersfield, CA
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Robert Padgett
Senior Account Executive
The Dolphin Group
Sacramento, CA
KarenBeth Traiger
Elementary Science Teacher
Graystone Elementary School
San Jose Unified School District
San Jose, CA
Heidi Perry
First Grade Teacher
North Davis Elementary School
Davis Joint Unified School
District
Davis, CA
Denise Van Horn
Fourth Grade Teacher
McSwain Elementary School
McSwain Union Elementary
School District
Atwater, CA
Matt P e r r y
Science Teacher
Sullivan Middle School
Fairfield-Suisun Unified School
District
Fairfield, CA
John Vogt
Middle School Science Teacher
Dover Middle School
Fairfield-Suisun Unified School
District
Fairfield. CA
Wendell Potter, Ph.D.
Vice Chairperson
Physics Department
University of California
Davis, CA
Gil Walker
Elementary Science Teacher
Gibson Elementary School
Woodland Joint Unified School
District
Woodland. CA
Wynette Sills
Farmer
Pleasant Grove Farm
Pleasant Grove, CA
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Laura Tower
Project Coordinator
California Foundation for
Agriculture in the Classroom
Sacramento, CA
R o g e r Sitkin
Farmer
Old Dog Ranch
Linden, CA
Casey Walsh-Cady
Research Assistant
California Department of Food
and Agriculture
Fertilizer Research and
Education
Program
Sacramento, CA
Nancy Stevens
Biology Teacher
San Rafael High School
San Rafael City High School
District
Santa Rafael, CA
Mary Yale
Middle School Science Teacher
Grange Middle School
Fairfield-Suisun Unified School
District
Fairfield, CA
Michael Toscano
Agriculture Teacher
Las Plumas High School
Oroville Union High School
District
Oroville, CA
4
Illustrators
Karin Bakotich
Sherri Freeman
Lavout, TvDinca and
Desian
Karin Bakotich
Sherri Freeman
Tami Gutschall
Lyn Hyatt
INTRODUCTION
The Science Framework for California Public Schools emphasizes the need to make science
education more meaningful to students so they can apply what they learn in the classroom to
their daily lives. Since all students eat food and wear clothing, one natural connection between
science and the real world is agriculture.
Agriculture is an enormous industry in the United States, especially in California. As more
rural areas become urbanized and more challenges exist to maintain and improve the quality of
the planet and feed the people of the world, it is extremely important to educate students about
their environment and about agriculture.
The concept of cycles is very broad and can be used throughout your entire science curriculum.
This unit “Starting All Over Again - The Cycles of Nature” focuses on plant nutrient cycles. It
stresses that, with few exceptions (meteorites, matter being released into space, etc.), there is
a finite amount of matter on our planet and this matter must be used over and over again. It also
illustrates that energy converts elements from one form to another and that only certain forms
of matter are usable by plants. Challenges facing agriculture are clearly illustrated as students
develop their definition of a cycle, establish the criteria needed to make a complete cycle and
analyze some of the cycles needed for the successful production of food and fiber.
“Starting All Over Again” is intended for use as a supplemental unit to the California Foundation
for Agriculture in the Classroom’s plant nutrient unit “How Much Is Too Much? How Little Is
Too Little?” The lessons can be incorporated as a sub-unit while plant experiments are in
process or can be interspersed throughout the unit at appropriate points. Middle school science
teachers can also incorporate single lessons from the unit into an already established
curriculum.
The California Foundation for Agriculture in the Classroom is dedicated to fostering a greater
public knowledge of the agricultural industry and seeks to enlighten students, educators, and
leaders in the public and private sector about agriculture’s vital, yet sometimes forgotten, role
in American society and the effect all citizens have on agriculture’s well being. Please contact
the Foundation for assistance with the integration of agriculture into your curriculum.
Comments on this unit or on other Agriculture in the Classroom resources are always welcome.
OBJECTIVES
The students will:
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Understand the meaning of a cycle.
Develop a basic understanding of the major cycles of nature.
Relate the major cycles to the production of food and fiber.
Demonstrate how microbial decomposers are part of the “recycle” systems in nature.
Understand how the nitrogen cycle fits into the overall cycles of nature.
Analyze how humans can atter the balance of cycles.
KEYVOCABULARY
A spergillus
Cycle
Ecosystem
Leaching
Microorganism
Nitrite
Protein
Bacteria
Decomposer
Energy
Legume
Neurospora
Nitrogen-Fixing Bacteria
Recycle
Compost
Denitrifying Bacteria
Fungi
Matter
Nitrate
Penicillium
Rhizopus
Root Zone
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BULLETIN BOARD IDEAS
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Enlarge transparencies of cycles and transfer to art paper; have students color the diagrams.
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Make collages of cycles. Have the board entitled “Cycles, Cycles, Everywhere”.
SEQUENCE OF ACTlVlTlES
All Aboard the Carousel
Read All About It
This Rotting World
Around and Around Nitrogen Goes!
Play It Again, Nitrogen!
EXTENSION ACTIVITIES
A variety of activities is described in detail in the Teacher Resource section of the “How Much Is
Too Much? How Little Is Too Little?” unit available from the California Foundation for
Agriculture in the Classroom.
EVALUATION
The evaluation activities are consistent with CLAS models. Embedded Assessment includes
writing and drawing responses to readings, role playing and other knowledge application
projects. Lab journals and lab write-up activities can be incorporated into Student Portfolios.
ALL ABOARD THE CAROUSEL
(A Lesson on Cycles)
PURPOSE
The purpose of this lesson is to develop an understanding that many different cycles operate in
the environment and that cycles are continuous and repetitive. This lesson will sense as an
initial assessment of your students’background knowledge on natural cycles in ecosystems.
CONCEPTS
By passing through a series of stages or steps, matter can be changed from one form to another
and back again creating a cycle or a recycling process.
Matter needed to sustain life is cycled and recycled within an ecosystem.
MATERIALS
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Blank transparencies
Clean white sock
Scratch paper
Transparency markers (1 per group)
Water cycle transparency
Mud or dirt
Overhead projector
TIME
2 fifty-minute sessions
BACKGROUND INFORMATION
On Earth, there is ,a finite amount of matter available which is used over and over again. Matter
is needed to sustain life and is dependent on this recycling.
Energy is a necessary input for some steps of a cycle and is an output of other steps in a cycle.
Examples of energy connections to cycles include sunlight causing evaporation and the synthesis
of sugars and starches in plants, wind causing evaporation and erosion, and the increase or
decrease in temperature or movement. As you discuss cycles, remember to mention the need for
energy to make cycles operate.
PROCEDURE
1 . In the front of the room, where students are likely to notice, hang up a clean white sock.
Leave it there until you are ready to begin the lesson.
a Take the white sock that has been on display and have a student make it noticeably dirty
by rubbing it in mud or dirt.
b. Ask the students what happened to the sock. Can it become a clean white sock again?
How? Have the students write and/or draw their ideas on a piece of paper.
C.
As a class, list the steps or stages the sock goes through from clean to dirty until you’ve
gone full cycle. Draw a class agreed upon illustration of the clean/dirty sock cycle. An
example of the cycle is shown in the following diagram.
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Aluminum can recycling
Paper/newspaper recycling
Glass bottle recycling
Clean/dirty dishes
Seed to plant to seed
Four seasons
Butterfly metamorphosis
Lunar cycle (night/day)
b. Have students choose one cycle, make sure it holds up to the criteria of a complete cycle,
and then draw a diagram of it on scratch paper. Once the group has agreed on the cycle,
have them draw their cycles creatively and neatly on overhead transparencies.
c.
Have students present their cycle to the class using an overhead projector.
CONCLUSION
There is a continual cycling and recycling of materials in the environment. Changes in one cycle
may affect other cycles. There is a finite amount of matter on Earth which is used over and over
again.
VARIATION
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Instead of using overhead transparencies to illustrate various cycles, have students use
large pieces of butcher paper and colorful markers. Post the diagrams around the room.
EXTENSIONS
.
Invite a professional recycling manager, such as a car or newspaper recycler, to explain
what is done in his/her operation.
.
Invite a farmer to discuss how nutrients are recycled in his/her operation.
.
Invite a professional launderer to discuss how clothes are cycled in their operation.
.
Have students examine the cycles that precede or follow their cycle. For example, the sock
cycle is affected by many other cycles, i.e. the growing of cotton to make the sock, the
production of the soap, the cleaning of waste water, etc.
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Examine how energy flows through cycles.
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PROCEDURE
1 . Explain to the students they will read about different cycles that occur in nature and
examine diagrams that illustrate the cycles. They will use a method that wil! help them pick
out the main points of the reading and share what they read with other students.
2. Have each student read individually the “Nitrogen and the Nitrogen Cycle” handout. Then
have the students do the “Think-Pair-Share” activity described below.
Instructions for “Think-Pair-Share”:
“Think-Pair-Share” is a quick way to have student partners exchange their thoughts and
ideas on a topic, or react to a new question.
a)
After the students have read the handout, have them think about them for a minute or
two.
b)
Have them share their thoughts and ideas with a partner.
The intent of the activity is not to have students do extensive problem solving, but to
provide a motivating conversation as preparation for the next activity. “Think-PairShare” is a good warm up as an anticipatory set for a lesson on new material or as a
bridge from a directed lesson to a group writing assignment or project.
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3. Using the nitrogen transparency, summarize with the students the important points of the
nitrogen cycle. Be sure to:
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identify the key organisms in the recycling of a molecule of nitrogen.
determine how raising various crops affects the nitrogen cycle.
discuss how fertilizer application affects the nitrogen cycle.
discuss how nitrogen can become a pollutant.
discuss the possibility of nitrogen pollutants being recycled into a usable form of
nitrogen.
4. Now the students will learn about three other cycles -- the carbon oxygen cycle, water
cycle and rock/soil cycle. They will learn about these by using the Jigsaw procedure
described below.
Jiqsaw Readina Activity:
a) Divide your students into heterogeneous groups of three. There should be a strong reader
in each group. You may choose to use these groups for this reading assignment, the
upcoming laboratory experiment and “Around and Around Nitrogen Goes.”
W Pass out one packet of reading material to each group. Each packet should contain the
following papers clipped together:
1
‘The Carbon/Oxygen Cycle” reading assignment
“The Water Cycle” reading assignment
1
“The Rock/Soil Cycle” reading assignment
3 “Starting All Over Again” activity sheets
1
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4.
Examine igneous, sedimentary and metamorphic rocks. Using sand
see if you can create quick weathering and “soil” production.
on each rock,
5. On a large tilted tray, create a sand and stone hill. Gently water the hill with a fine
spray. Notice the “erosion” that occurs down the hillside and the formation of lakes and
deltas.
6. Using word processing programs such as The Storv Weaver, have students write a story
titled “My Life as a Raindrop” or “My Life as a Grain of Sand.”
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Name----
-m----___
Starting All Over Again
In the space below, draw and briefly describe the way you
think the
cycle operates.
What I Think...
After reading about the cycle, draw and briefly describe t h e
cycle with any changes you would m.ake.
What
I
Learned . . .
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the soil leaving nitrogen that can be used by the next crop -- usually a crop that cannot fix its
own nitrogen.
Nitrogen gas is also converted into commercial inorganic fertilizers in factories. These
fertilizers contain nitrogen in a form plants can use.
NITRIFICATION
Another part of the nitrogen cycle transfers nitrogen from dead plants and animals into the soil.
This is called nitrification. As you know, certain bacteria and fungi decompose dead plants
and animals. As they do this, they produce ammonia. Special nitrifying bacteria “eat” the
ammonia particles and release nitrites. Then, special nitrate bacteria “eat” the nitrites and
release nitrates -- a nitrogen form that plants and animals can use. As you can see, bacteria
are very important tiny organisms that we depend upon for survival.
Bacteria
&
Fungi
Dead Plants - - and Animals
Nitrifying
Bacteria
Ammonia
Nitrate
Bacteria
- - - - Nitrites - -
Nitrates
- - New Plant Growth
DENITRIFICATION
Denitrification is the process in which nitrogen is returned to the air as nitrogen gas (NJ .
This process is also completed by a group of bacteria -- denitrifying bacteria. These bacteria
are found in the soil. Volcanic eruptions also return nitrogen gas to the air.
HUMANS AND THE NITROGEN CYCLE
Human interactions with the environment can influence the nitrogen cycle in many ways. The
burning of fossil fuels to produce electricity and operate cars releases nitrogen compounds into
the air. Human waste is high in nitrogen and if improperly processed, it affects waterways.
Farmers have the challenge of making sure that the appropriate amounts of usable nitrogen are
available to crops at the appropriate times. Too little nitrogen will produce unhealthy plants.
Heavy watering or heavy rains may result in moving nitrogen below the root zone of plants
where it cannot be utilized. This leaching, or the application of too much nitrogen fertilizer,
can cause groundwater and stream contamination. Laboratory and field research, in the area of
the nitrogen, is an ongoing process. The goal is to ensure that the nitrogen cycle remains in
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balance so that plant and animal life can continue to exist on Earth.
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READING #l
THE CARBON/OXYGEN CYCLE
Imagine, for a second, what Earth
would look like without plants. If you visualized an empty,
desolate planet, you are probably right. Animals depend on plants for food. Without plants,
animal life would not exist.
PHOTOSYNTHESIS
Plants, for many reasons, are extremely important living things. Green plants use sunlight,
water and carbon dioxide to produce food for themselves. When they do this, oxygen is released.
This process is called photosynthesis. Only plants and a few bacteria are capable of
performing photosynthesis. Plants are the basic food source for all animals.
RESPIRATION
Animals use the oxygen, released by plants and certain bacteria, in their bodies. When they do
this, carbon dioxide is released. This process is called respiration. Plants use the carbon
dioxide produced during respiration to begin photosynthesis again. Plants also respire and
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produce small amounts of oxygen.
The amount of carbon dioxide and oxygen in the atmosphere is affected by many things -weather, pollution, increasing or decreasing the number of plants and animals on the planet and
many other human activities.
* Farmers do many things to keep the carbon-oxygen cycle in balance. They plant crops in
appropriately sunlit places, provide water to their crops so photosynthesis can occur, prune
orchards to make sure the leaves get the proper amount of sunlight and fertilize plants so that
proper nutrients are available for plant growth.
* Foresters constantly examine the carbon dioxide-oxygen balance in forests and do what is
needed to maintain a proper balance of these elements. This includes planting and removing
trees from only certain locations and monitoring pests and the water supply.
* Air pollution scientists analyze how air composition is affected by air pollution. One major
pollutant is carbon monoxide (CO), which is emitted from cars and factories. Since carbon and
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oxygen are the elements that make carbon monoxide, this pollutant affects the carbon/oxygen
cycle.
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THE CARBON/OXYGEN CYCLE
Carbon Dioxide
in the Atmosphere
(Oil, Gas, Coal)
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THINK ABOUT IT!
t
Where do people get their drinking water from?
*
Where do farmers get water for crops and animals?
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How is water used in cities and in agriculture returned to the environment?
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The human population continues to grow. How does this growth affect the water cycle?
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Why is the amount of fresh water available in California always an issue?
THE WATER CYCLE
Condensation
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SOIL
Any type of rock can be weathered to form tiny particles of dirt. These dirt particles contain
many of the nutrients plants need to grow. Soil is made of dirt particles, which originally came
from rock (sand, clay, etc.) and dead plant and animal matter. Soil also contains many living
things such as bacteria, fungi, viruses, worms and microscopic animals.
SOIL
Rain, ice, thawing, and
freezing break down
rocks and some mineral
particles.
Simple plants and animals
begin to live on weathered
rock.
Lichens produce acid;
organisms die and
deposit matter (humus).
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Cover of vegetation is
formed; soil contains
Top layer of soil is formed
and is able to support plant
Plants establish their roots in the top layers of soil.
precious commodity.
In most areas of the world, topsoil is a
It is important to properly maintain this topsoil by not letting it erode
into rivers and streams or by contaminating or overusing it. In order to conserve topsoil,
farmers plant rows of trees between and at the edges of fields to cut down the effects of wind and
water erosion, farmers try to keep unplanted soil to a minimum, and they replenish the soil
with nutrients they remove from it.
Farmers continually look for new techniques to maintain
soil quantity and quality.
THINK ABOUT IT!
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What can you do around your home to reduce soil erosion?
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What happens to topsoil that is eroded?
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Where in the world is the amount of land and soil increasing (getting larger)?
How is the amount of topsoil available for plant growth affected by the increase of city
sizes?
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How could a farmer increase the amount of topsoil available on a certain plot 01* land?
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THE ROTTING WORLD
(How Microbial Decomposers Fit Into the Nitrogen Cycle)
PURPOSE
Students now have an overview of many important cycles in nature. The purpose of this
experiment is for students to see, first hand, the microbial decomposition process of plant
material. Visual examination of fungi will also be possible. The students will relate this
information to the nutrients plants require for growth and to the nitrogen cycle.
CONCEPTS
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Fungi and bacteria help to break down plant and animal material, returning simple
compounds to the air, water and soil to be used again.3
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Several different kinds of fungi and bacteria may grow on the same foods.
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More than one kind of organism may be necessary to completely decompose a particular food.
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Nitrogen is one nutrient that plants require. It is often returned to the soil as organic
matter (decomposed dead plants and animals).*
MATERIALS
Several slices of white bread without preservatives
Chopped food -- apple, potato, orange, beans, grapes, cheese and tomato (6 kinds)
Butter knife -- at least one
Plastic bags (self sealing) -- six for each group
Water -- 1 gallon of water with 2 handfuls of dirt added to it
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Warm storage space, away from light
Labels -- for each group‘s test materials
Plastic milk carton -- 1 gallon
TIME
1
1
10
2
hour - teacher preparation
fifty-minute session -- introduction and set up
- 15 minutes daily for 5 to 10 days -- observations and journal writing
forty-five-minute sessions -- final observations and lab write-up
BACKGROUND INFORMATION
This lab will allow students to see how plant material decomposes and, therefore, indirectly
shows how the nitrogen in plants is returned to the environment. It is difficult to show changes
in the nitrogen content of air, water and soil without complex experiments. Discuss with your
students that nutrients are not only returned to the soil for reuse but that the organic matter
also improves soil quality.
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without your “answers” being imposed on them. The experiment will provide scientific
evidence to support the appropriate concept.
3. Show students different food items -- oranges, potatoes, bread, etc. Have them think about
what would happen if fungi and bacteria interacted with these foods. Ask them to list
interrelationships between fungi and bacteria and these food items.
4. Divide students into groups of three or six. Using the procedure described below, have each
group test for the decomposition of bread and of at least five other kinds of food.
a
Place 2 tablespoons of chopped food or 1 slice of bread into a resealable sandwich bag.
Each food should be in a separate bag.
b. Add 5 ml of the dirty water solution. This inoculates the food with decomposers.
c.
Seal bag and store in a warm dry place. Have students record, in their lab notes or
journal, the date they started this experiment. Have them predict what will happen.
d.
Each day, examine the contents of the bags. Have students indicate in their notes how the
food looks each day and note the number of days it takes for each kind of food to show the
presence of fungi.
e. Have students continue obsenring the food, note what happens to the food, and what
changes they see in the fungi.
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f.
DO NOT OPEN THE BAGS! Some students are allergic to fungi and the exact content of
microbes is not known.
g.
Have students complete the lab worksheet provided.
5. Using a large sheet of butcher paper (or 8 112” x 11” blank white paper), have student
groups relate their decomposition experiment to the environment. Have them illustrate and
explain the importance of bacteria and molds and/or what the planet would look like without
decomposers.
6. Have students share their illustrations and thoughts with the rest of the class.
CONCLUSION
Molds and bacteria decompose plant and animal matter. Decomposers are an important
component in the cycles of living things. They return, back to the environment, the nutrients
that were removed from the soil and air when the plants or animals grew.
EXTENSIONS
1 . Model of lake eutrophication
To determine how the products of decomposition affect the growth of algae or pond plant
(such as duckweed, Anacharis) in water, perform the following experiment:
.
Fill two large jars or goldfish bowls with water obtained from a stream, pond or
swimming pool in which algae is present.
.
Place both bowls in the light or provide an artificial light source. Leave one bowl
untouched. To the second bowl, add 5 ml of liquid from grape, bean or potato
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Name-__-____ --D a t e
P e r i o d
THE ROTTING WORLD
(Microbial Decomposition)
INTRODUCTION
Fungi, bacteria, earthworms, slugs and mushrooms are part of a special group of organisms
called decomposers. Decomposers break down dead plant and animal material and the waste
products of animals. They are an important component of the nitrogen cycle. Imagine what
Earth would look like if nothing ever decomposed!
In this experiment, you will observe decomposers at work and record your results. You will
put food into sealed plastic bags and let them sit for about one week. Follow the procedure below
and any other instructions your teacher gives you.
What do you think will happen to the food in the plastic bags?
MATERIALS
.
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Foods -- white bread with no preservatives, chopped apple, potato, grape, orange, bean,
tomato, cheese (choose 4-6)
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Plastic bags that self seal or have twisty ties for each food
Water with soil added to it
Labels for each bag
Graduated cylinder for measuring water
Magnifying lens
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PROCEDURE
1 . Place 2 tablespoons of chopped food or 1 slice of bread into the plastic bag. You will have
a separate bag for each food.
2. Label each bag with the food name and your group name, letter or number.
3. Add 2 ml of the dirt/water mixture.
4.
Seal the bag.
5. Place in warm dark spot.
6. Examine daily and keep a record of your results in your science notebook or on a sheet of
paper. Include the date and the changes that did or did not occur in the bag. Notice the
color of the organisms growing. Use a magnifying lens to see the detail of the fungi.
Draw any pictures that help explain what is happening.
7. Never open up the bag!
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8. At the end of the experiment, complete the chart and answer the summary questions.
9. Dispose of the bags as indicated by your teacher.
30
N am e ______-_-________-_
3. How were the fungi in the diflerent bags alike?
Different?
4. Why do you suppose a little dirt was added to the water?
5. Why are decomposers important?
-
6. Would you recommend that a farmer includes organic matter in the soil?
Why/why not?
7. Discuss two things you learned during this experiment.
-
32
AROUND AND AROUND NlTROGEN GOES!
(A Nitrogen Cycle Game)
PURPOSE
This game will reinforce the student‘s understanding of the nitrogen cycle and illustrate how the
cycle affects plant growth. Students will see how incidental and planned actions affect the
nitrogen cycle.
CONCEPTS
l
The nitrogen cycle is complex and includes interactions between a variety of living and nonliving things and their environment.
l
The nitrogen cycle is a key cycle for the survival of plants and animals.*
l
The nitrogen cycle is sensitive to a variety of incidental and planned interventions?
MATERIALS
For each group of 3 or 4 students:
.
.
.
-
1 “Nitrogen Game Card” for each student
100 tokens such as pennies or beans
1 set of “Around and Around Nitrogen Goes” task cards -- cut up
TIME
1 thirty-minute session
BACKGROUND INFORMATION
The game the students will play is a simplified model of the nitrogen cycle. Many parts of the
nitrogen cycle are eliminated to make the game usable by students. Discuss with your students
that this is a very simplified version of the nitrogen cycle and that the purpose of this activity
is to show how sensitive the nitrogen cycle is and how particular actions affect it.
PROCEDURE
1 , Explain to your students that they are about to play a game that shows the impact of various
actions on the nitrogen cycle. Review the nitrogen cycle, if necessary. Discuss that for the
sake of this game, nitrates will represent all forms of nitrogen plants can use.
2
Divide students into groups of 3 or 4.
3
As a class, discuss the game instructions. You may choose to make an overhead transparency
of a “soil game card” and demonstrate one or two of the task cards.
4
Distribute the appropriate materials to each group. Explain to the students what they should
do when they are finished with the game.
5
At the conclusion of the game or class period, help students determine the winner of each
group’s game by using the following criteria:
33
-
AROUND AND AROUND NITROGEN GOES!
Student Instructions
INTRODUCTION
Plants require many nutrients for growth. As you already know, one of the nutrients plants
require is nitrogen. Although the Earth’s atmosphere is over 70% nitrogen gas, plants are
unable to use it. Plants can only absorb nitrogen in a few forms, one of which is nitrate.
OBJECT OF THE GAME:
The object of the game is for you to end up with the ideal amount of nitrates in your plot of soil.
The person with the ideal number of nitrate particles in his/her plot of soil will have the most
abundant crop and will be the winner of the game! The ideal number will be revealed at the end
of the game.
Game Instructions for groups of 3 or 4 people:
1 . Pass out one soil plot to each student.
2. Shuffle the task cards and put them face down in a place where everyone in your group can
reach them.
Put 10 nitrate tokens in each person’s soil plot. The tokens represent nitrates, a source of
nitrogen which is usable by plants.
Place the remaining tokens in a central location for use by the entire group. This central
location will represent the Earth’s atmosphere.
In a fair manner, determine which student will go first, which student will go second, etc.
Have the first player draw a task card and read it to the group. Have the farmer do what the
card indicates.
.
If the card indicates to add nitrates to the soil, do so by taking the appropriate number of
nitrogen particles from the “atmosphere” and placing them into the soil.
.
If the card indicates to change one of the nitrate particles into an unusable nitrogen
particle, remove one nitrate particle from the soil and place it where the card indicates.
.
If the task asks you to remove more nitrogen from your soil than you have, remove as
many particles as you can and then proceed to the next farmer.
7. Continue this procedure with each player until all of the task cards are gone OR your teacher
calls time.
8. At the conclusion of the game, have each student count how many nitrate panicles is in
his/her soil. Listen to your instructor to determine who won the game.
-
35
-
AROUND AND AROUND NITROGEN GOES!
Task Cards
A farmer plants a cover crop of beans,
Beans are legumes. Legumes fix
nitrogen into the soil. Add 2 nitrates to
your soil.
A farmer buys manure from his
neighbor’s dairy to spread around his
grapes. Manure is high in nitrogen
which is decomposed into nitrates.
Put 1 nitrate in your soil.
It is late winter and there has been
much winter rain. Nitrogen is lost due
to leaching. Remove 3 nitrate
particles. There are still some fallen
leaves left under the trees. Decomposers live in these leaves. Add 2
nitrates back into your soil.
There is a big lightning storm in the
Midwest corn belt. Lightning converts
some nitrogen gas into nitrates. Add 1
nitrate to your soil.
-
A classroom makes a compost pile.
After two weeks, the students notice
the organic matter decomposing and the
soil is very warm. After one month,
the class spreads the decayed organic
matter into the school garden. Add 1
nitrate to your soil.
+ The farmer harvests the rice in his
field but leaves the stubble from the
plants. Many animals and decomposers
eat and live in this stubble until it
gradually rots away. Add 2 nitrates to
your soil.
Early Native American farmers planted
beans around their corn plants for
natural fertilizing. Beans are in the
legume family and can fix nitrogen.
Add 1 nitrate to the soil.
Denitrifying bacteria convert nitrogen
in animal manure to nitrogen gas.
Remove 2 nitrates from your soil.
-
37
AROUND AND AROUND NITROGEN GOES!
Task Cards
-
A golf course owner adds the
recommended amount of ammonium
sulfate to the golf greens. Add 2
nitrates to your soil.
A septic tank leaks raw sewage
(which is high in nitrates) into the
water which you use to irrigate your
fields. Add 8 nitrates to your soil.
A forest is left undisturbed and the
soil contains denitrifying and
nitrifying bacteria. Remove 2 nitrates
from your soil and then add 2 nitrates
back into the soil.
You grow corn on your land for 3
seasons straight without adding any
type of fertilizer or organic matter.
Remove 3 nitrates from your soil.
A farm using sustainable agricultural
practices returns as many nutrients to
the soil as are removed from the soil
by crops. Do not add or remove any
nitrate particles.
A peanut farmer inoculates the soil
with Rhizobia bacteria. These bacteria
can convert nitrogen gas to nitrates.
Add 4 nitrates to your soil.
An “el nino” (a warm water current)
increased the water temperature of
the Sacramento Delta waterways.
Denitrifying bacteria began to rapidly
flourish. Remove 2 nitrates from your
soil.
A large marine estuary was contaminated
with oil from a leaky oil barge. A lot of
the natural bacteria were destroyed.
Remove 6 nitrates from your coastal soil.
.
39
-
PLAY IT AGAIN, NITROGEN!
(A Nitrogen Cycle Role-Play)
PURPOSE
This lesson will connect the previous activities on cycles and decomposition by having students
closely examine the nitrogen cycle. The decomposers in “The Rotting World” experiment are
animated in a role-playing scenario. Through the role-play of the nitrogen cycle, the students
will consider the agricultural and environmental consequences that occur when the nitrogen
cycle is interrupted.
CONCEPTS
l
The nitrogen cycle is complex and includes interactions between plants, animals, special
bacteria, decomposers, air, water and soil.
l
The nitrogen cycle is a key nutrient cycle for the survival of plants and animals.
l
The nitrogen cycle is sensitive to human interventions and disruptions.
MATERIALS
l
l
_-
.
.
Transparency of “Nitrogen Role-Play” classroom diagram
Room deodorant spray (to represent air pollution)
Baby powder or cornstarch (to represent fertilizer)
“Nitrogen Ready...Lightning...Action” role-play cards (cut up)
TIME
1 thirty-minute lesson
2 fifty-minute lessons
2-3 thirty-minute group work sessions
1 twenty-minute presentation period for groups
BACKGROUND INFORMATION
Grade level and class disposition should be considered when preparing and organizing for the
role-play activity. Make appropriate procedural changes to meet the needs of your students and
classroom. Perhaps the activity can be completed outside.
If you have not attempted a role-play with your students before, the following warm up
suggestions may be helpful:
.
.
.
1
Explain to the students that they are going to enact a situation.
Have the whole class participate in sample role-plays to lower their anxiety levels and
inhibitions. (Example: Have students pretend they are licking an ice cream cone. Then say,
“You’re outside and it’s 90 degrees“. Have students demonstrate what would happen.)
Have the students make suggestions for rules of action (noise level, movement, staging, etc.)
that will facilitate a successful role-play.
The role-play will help reinforce the idea that humans do affect various cycles of nature. They
will see how their individual actions can make a difference in regard to environmental q uality.
40
f.
Using a predetermined “Freeze” signal, stop the cycle and do the following:
1) Spray the deodorant (an air pollutant) in the air over the nitrogen group. Have them
role-play what might happen.
2)
Put powder (fertilizer) on the ground near the bacteria group.
Play what might happen.
Have them role
3 ) Remove half the students from ?he nitrogen group and half from the bacteria group.
Have the class try to resume the cycling process. When there seems to be some chaos
and breakdown, stop the role-play and have students return to their seats for
discussion.
g.
Discuss with the class how the cycle was working before you intervened with other
chemicals. What happened after? What specific examples could the deodorant and
powder represent? (pollution, fertilizers, pesticides, etc.) At what stage would these
likely affect the nitrogen cycle? List student responses on a chalkboard diagram of the
nitrogen cycle. Have students label their diagrams in their science journals/lab
notebook with the various potential disruptions to the cycle process.
4. Review the role-play and the possible disruptions to the nitrogen cycle. Discuss what
happens if the nutrients provided by the nitrogen cycle cannot get to plants or cannot be
produced due to a breakdown in the cycle. What steps are necessary to provide plants with
nutrients when man alters the natural cycle?
a
With students working in groups of three (same groups as reading groups), assign
students the task of creating a visual presentation of the nitrogen cycle, a critical human
intervention and a solution to the potential problems that the intervention would cause.
The students can do a series of cartoon/storyboard posters, animation via flip books, a
paper scroll movie, etc. If computers are available, the HyperCard program can be used
to create interesting projects. Allow the groups a few class periods to work on their
projects together.
b. Have each group present their project to the class, explaining the critical intervention
and how they chose to solve the problems it caused in the natural nutrient cycle.
Students may choose to use an example from one of the cards in the “Around & Around
Nitrogen Goes” game.
CONCLUSION
In order to ensure the continued survival of living organisms, caution and careful planning
must be used when intervening with natural nutrient cycles within ecosystems.
-
42
NITROGEN READY . . . LIGHTNING . . . ACTION!
(Role-Play Cards)
(Make one copy of this handout and cut on the dotted lines. Place the strips in a hat or container
and have each student group pick a paper strip. This will be the group they will represent in
the role-play.)
Read to students:
Above ground are the wonders of the plant and animal kingdoms surrounded by an ever changing
sky. Below ground lies the mysteries of decomposers, nitrates and elaborate root systems. The
nitrogen cycle involves experiencing both worlds. The actors in the nitrogen cycle will be
represented by the following groups -- decomposers, nitrates, nitrogen fixing plants,
denitrifying bacteria, green plants, animals and nitrogen gas.
_____~__---~__~__---~~~~~~~~~~~~~~~~~~~~~~~~~~~~~----~~~---~~_____
GROUP # 1 - DECOMPOSERS
The Decomposers capture dead plant and animal matter that’s working its way down into the
soil. They change them into nitrates. Each time the Decomposers capture decomposing matter,
it must release a cleaned up nitrate. The Decomposers are a hard working group. They take the
yuck of the Earth and change it into something very useful. It’s a dirty job, but someone has to
do it.
(Figure out where you are coming from, where you are going and how you will act out your job
at role-play time.)
GROUP # 2 - THE NITRATES
The Nitrates are a very motivated group. They have been reformed, changed and given a new
mission in life. They must make it back to the wonders above ground. It’s a long journey up
through the roots of plants and they allow these plants to grow. They come from the
Decomposers or from the Legumes. The Nitrates believe they can make a difference. Cheer
these guys and gals on.
(Figure out where you are coming from, where you are going and how you will act out your job
at role-play time.)
GROUP # 3 - THE NITROGEN-FIXING PLANTS
The Legumes are a very select group; kind of snooty and they like to toot their own horns. The
Legumes can take nitrogen from the atmosphere and turn it into nitrates. It’s a comfortable and
quick way to do the cycle, a lot quicker than going through decomposers. If you’re a lucky
nitrogen molecule, you can make your way past the yuck, via the Legumes.
(Figure out where you are coming from, where you are going and how you will act out your job
at role-play time.)
44
Window T c
Window
8%
00
OA
“Gresn Plants”
arrows.
“Animals” fi
“DecomDosers” ’
Chalkboard
EDUCATIONAL RESOURCES
Atlas of Environmental Issues, Nick Middleton; hex Publishers Ltd., 1989. (800) 3228755.
Student reference that explores global environmental issues including soil erosion, air
pollution and acid rain.
Banana Slug String Band, P. 0. Box 2262, Santa Cruz, CA 95063. (800) 476-5776.
This educational band, geared towards elementary students, provides a variety of educational
music materials about environmental science concepts.
“Bottle Biology”, Bottle Biology Program; University of Wisconsin-Madison, Department of
Plant Pathology, 1630 Linden Drive, Madison, WI 53706. (608) 263-5645.
Bottle Biology is an inexpensive, motivating way to teach hands-on biology using one and two
liter plastic bottles. Sign up for their newsletter.
California Department of Water Resources, P. 0. Box 942836, Sacramento, CA 94236
Write and request a list of educational materials.
California Fertilizer Association’s Lending Library of Motion Pictures, 1700 “I”
Street, Suite 130, Sacramento, CA 95814. (916) 441-1584.
A variety of videos and slides discussing fertilizer use and water quality are available.
California Foundation for Agriculture in the Classroom, 1601 Exposition Boulevard
FB-16, Sacramento, CA 95815. (916) 924-4380.
The Foundation has a wide variety of materials for educators that promote a better
understanding of California agriculture. Request a Teacher Resource guide and to be put on
their mailing list.
Conserving Soil, National Association of Conservation Districts Service Department, P. 0.
Box 855, Dept. SCS, League City, TX 77573. (916) 324-0864.
A teacher guide with middle school/secondary activities with transparencies about soil
history and uses. Approximately $9.
Ecoloav. Usborne Science and Exoeriments, Usborne Publishing Ltd., 1 9 8 8 .
Excellent non-fiction references for middle grade students. Good section on cycles in nature.
Available at most bookstores.
Environmental Science, Merit Badge Series, Boy Scouts of America; Irving, TX, 1983.
(800) 323-0723.
Merit badge pamphlets are inexpensive and are written for middle school students. Many
have simple overviews of how cycles are part of the environment.
48
GLOSSARY
Ammonia (NH3) -- one of the products in the nitrogen cycle; a gas
Ammonium (NH4+) -- a form of ammonia that is usable by plants in their growth cycle;
often supplied in organic fertilizers
A spergillus
-- one kind of fungus that is responsible for decomposition
Bacteria (plural of Bacterium) -- microscopic single-celled organisms that may group in
colonies; bacteria may be helpful or harmful to plants, animals and humans; some are involved
in the decomposition of organic matter
Compost -- a mixture made of decaying organic material; it is used to fertilize plants and
amend soils
Cycle -- a series of events or operations that reoccur in a regular pattern
Decomposer -- a living organism that breaks down organic matter; includes such organisms
as bacteria, fungi, nematodes, and earthworms
Denitrifying bacteria -- a group of bacteria that remove nitrogen from organic material
and return it back to the atmosphere as N2
Ecosystem -- plants and animals that live together in an area and interact with each other and
the air, soil and water around them
Energy -- the ability to do work; human and animal life depend on energy; most energy comes
from the sun; plants convert light energy into the chemical energy stored in food; energy is
needed to make the cycles of nature flow
Fungi (plural of fungus) -- one of many kinds of decomposers of organic materials, the
organisms get their energy from the breakdown of such matter; they do not contain chlorophyll
Legume -- normally a plant that has pods; often help with nitrogen fixation; includes beans,
peas, alfalfa
Microorganism -- a living organism that can only be seen with magnification; the group
includes bacteria, fungi, protozoa and viruses
Neurospora -- a type of fungi that is responsible for decomposition of organic material,
usually black in color
Nitrate (NO33 --
a form of nitrogen that is usable by plants for growth
Nitrite (NO,? --
a form of nitrogen that is converted to nitrate by nitrogen fixing bacteria
Nitrogen (N2) -- an element that naturally exists in air and is needed by plants to produce,
among other substances, proteins, chlorophyll, DNA and RNA
Nitrogen-fixation -- the transformation of atmospheric nitrogen (N2) into forms available
for plant growth such as nitrites, nitrates and ammonium compounds; often performed by a
bacterium called Rhizobium
50
FOOTNOTES
The chapter and page numbers refer to the 1990 Science Framework for California Public
Schools adopted by the California State Board of Education.
1 ) Chapter 5; C-2, pp. 138-141.
2) Chapter 5; A-l, pp. 116-119.
3 ) Chapter 4; B-4, pp. 96-98.
4 ) Chapter 4; C-l, p. 99.
5 ) Chapter 4; B-3, p. 96.
6 ) Chapter 5; A-4, p. 125.
-
.-
52
-
Nitrogen-fixing bacteria -- bacteria that convert atmospheric nitrogen into forms that
are usable by plants
Nodule -- a little knot or bump found in roots of plants; normally filled with a bacterium
called Rhizobium that performs nitrogen fixation
Organic Matter -- material in soil made from the decomposition of plants and animals; it
increases the soil’s ability hold to water and air
Penicillium -- one of a group of fungi that decomposes organic material; frequently found on
oranges; deep green color
Photosynthesis -- the process in which sugars and starches are made from carbon dioxide,
water and the use of sunlight
Protein -- an organic compound produced by plants and animals containing carbon, hydrogen,
oxygen and nitrogen; necessary for plant and animal cell growth
Recycle -- the reusing of a material over and over again
Soil -- the top portion of the Earth’s surface that is used to grow plants; consists of organic
inorganic substances
Rhizopus -- one group of fungi that decomposes organic material; black color; frequently
found on bread
51
-
-
Once There Was a Tree, Natalia Romanova; Dial Publishers, NY, 1985.
A popular picture book available in most bookstores which presents the cyclical nature of
living things.
One Leaf Fell, Toby Speed; Stuart, Tabori and Chang Publishers, NY, 1993.
A beautifully illustrated picture book that shows a cycle in nature. May be used with the
introductory lesson.
Orqanic Soil Amendments and Fertilizers, David E. Chaney, et al.; Regents of the
University of California, Division of Agriculture and Natural Resources, 1992.
This $5.00 booklet is a guide to organic materials used to enhance soil quality and promote
plant growth, which differ from synthetic fertilizers and amendments in that they are
derived specifically from plants or animals. To order, write to ANR Publications,
University of California, 6701 San Pablo Avenue, Oakland, CA 94608-1239 or call (510)
642-2431..
The Usbome Science Encyclopedia, Annabel Craig and Cliff Rosney; Usborne Publishing
Ltd., 1988.
A good student reference for quick answers to
weather, etc.
questions aoout matter,
energy,
-.
Water Education Foundation, 717 K Street, Suite 517, Sacramento, CA 95814.
(916) 444-6240.
This organization has a variety of well-balanced activities and materials
water issues.
to current
Western Fertilizer Handbook, Soil Improvement Committee and the California Fertilizer
Association:
The Interstate Printers and Publishers, Inc., 1990. (916) 441-1584.
This well organized book provides information on the nutrient requirements of plants and
nutrient management strategies. Great for background information on nutrient cycles and
fertilizers.
-
49
PLAY IT AGAIN, NITROGEN
(Project Ideas)
Storyboarding:
l
Using a series of eight
pictures or cartoons,
students represent the
stages of the nitrogen
cycle.
Flip Books:
l
Students use 10 - 15 index
cards, stapled at the side,
to animate the stages of
the nitrogen cycle,
Students draw each card
drawn in sequence.
Paper Movie:
l
Students tape a series of
drawings together in a
scroll. Using a large shoe
box and 2 paper towel
tubes, connect the scroll
to the paper tubes and cut
a window in the shoe box
.
Ird .
47
-
GROUP # 4 - DENITRIFYING BACTERIA
The Denites are like special agents. They’re here to find decaying and dead matter. They
process it quickly and put nitrogen back into the atmosphere.
(Figure out where you are coming from, where you are going and how you will act out your job
at role-play time.)
GROUP # 5 - GREEN PLANTS
The Green Machines gather in nitrates through their extensive root systems. They sort and
mix nutrients like a factory and are very organized and slick. They deliver shining and polished
products -- plants. Everyone wants their leaves, fruits and seeds. It’s a great life, but it has to
end eventually. Some of them get weak, lose their grip, fall to the ground. If they’re not
careful, along come the Animals with their huge appetites. Either way, they end up back in the
ground.
(Figure out where you are coming from, where you are going and how you will act out your job
at role-play time.)
GROUP # 6 - ANIMALS
The Animals consume just about everything. They particularly need the nutrients in plants.
They eat plants, digest them, incorporate the nutrients into their systems, and then discard
some matter as waste . . . without even a thought. Eventually the animals die.
(Figure out where you are coming from, where you are going and how you will act out your job
at role-play time.)
________~___~_______~~--~~~~~~~~~~~~~~~~~~~~~~~~~~~-~~~~~~
GROUP # 7 - NITROGEN GAS
________
The Floaters cannot do much up there in the atmosphere to help the plants and animals above
ground. These rich gases wander around looking for something to do until the legumes convince
them to hop a quick cycle for a change of routine. The less fortunate nitrogen gases just get
zapped by lightning every now and then, and fall to the Earth to join in with the Nitrates. Some
of the floaters are captured by fertilizer manufacturers and made into nitrates. Once they get
into the cycle, they usually have a pretty good time.
(Figure out what path each nitrogen gas molecule (each student in this group) will take through
the cycle -- some will be captured by bacteria in legumes, others made into fertilizers, some
will be zapped by lightning and some will act out your roles.)
45
EXTENSIONS
1 . After the groups have presented their nitrogen cycle projects, review all four cycles your
class studied -- the nitrogen, carbon/oxygen, rock/soil and water cycles and how they form
one large “Biological Cycle.”
2. To incorporate CLAS models of assessment into daily instruction, have the students write a
short opinion essay on the importance of understanding the effects of human interventions on
the environment. Be sure to have students justify their opinion by:
l
l
l
identifying a stage in one of the four cycles that is heavily impacted by human
intervention.
giving an example of an intervention and how it interrupts that cycle.
explaining what cautions and planning are necessary to avoid a breakdown in the
cycle.
4
43
PROCEDURE
1 . Prepare role-play cards for. each group described in “Nitrogen Ready...Lightning...Action!”
by writing each name on a large piece of construction paper. Make a copy of the script page
and cut on the dotted lines. Familiarize yourself with the classroom diagram for the rolePlay *
2. Review the conclusions and concepts of the decomposition lab and nitrogen reading
assignment. Discuss some of the key points with your students.
3. In order to get a better sense of what is happening during the nitrogen cycle, the class will
role-play the nitrogen cycle with student actors in the activity “Nitrogen Ready . . .
Lightning . . . Action!“. The procedure is described below:
a. Before explaining how the class will role play the nitrogen cycle, have the students
imagine a toy factory. Every job at the factory is important in assuring that the finished
product is put together properly. If one group moves too fast or too slow, it disrupts the
flow of the factory process. Organization and timing is key to a successful factory
process.
b. Decide on an imaginary separation in the classroom for above the ground and below the
ground. Arrange students into six groups of four to five each and a seventh group with
all remaining students. The seventh group can be the largest. Have student groups get
into their appropriate places above or below ground (see diagram). Tell students to keep
in mind that their group will need to stay organized and focused on timing in order to
maintain the proper flow of the nitrogen cycle.
C.
Post the large appropriate role-play signs near each group of students. Pass out group
role card scripts to each group and have the students in each group review what part of
the nitrogen cycle they will be acting out. Have the students determine and practice how
they will act out their part of the role-play. Students will choose a group spokesperson
who will tell the class what role they will play and what they do.
d.
Explain the role-play of “nitrogen” (group #7) going through the cycle via the other
class groups (#l - #6). Tell the students that nitrogen will enter into the cycle. Once
the cycle gets started, every group is responsible for keeping the whole class cycle
operating smoothly. It will be important to know what each group’s role is and where
they come from and go to in the cycle process. Model one nitrogen student going through
the decay cycle. Model another student through the legume cycle. Model a student
through the decomposition - denitrifying cycle. Explain that the legume and
decomposition cycles are short cut cycles, operating at the same time as the decaydecomposition cycle. Identify the deodorant spray as air pollution and the powder as a
fertilizer.
e.
Turn class lights off. “Nitrogen Ready . . . Lightning (turn lights on) . . . Action!” Place
two nitrogen students into the cycle. Wait until the denitrifying group pops out a
nitrogen student and add another student. Continue placing students into the cycle and
when the cycle is operating smoothly, let it go for a few minutes without your assistance.
Important reminder for each grou P:
-
In order to maintain the cycle, each time YOU gain a new member in your group from another
group, you must release a member to go onto the next appropriate stage.
41
AROUND AND AROUND NITROGEN GOES!
Task Cards
A farmer applies an ammonium
sulfate fertilizer to his crop in the
spring. This fertilizer was made by
changing nitrogen gas particles to
. ammonia which changes into nitrate.
Add 3 nitrates to your soil.
A farmer raises and puts millions of
earthworms into the soil. Add 1 nitrate
to your soil.
The lemon orchard, weighted down with
lots of fruit, is ready for harvesting.
No sooner does the crop get picked,
than the trees are in bloom again to set
more fruit. Not a lot of plant material
is returned to the ground from which it
came. Remove 2 nitrates from your
soil and return them to the
atmosphere.
A winter freeze slows down natural
processes. Nitrogen-fixing bacteria
die and the plants cannot absorb the
nitrogen they need. Nitrogen gas is
put back into the air. Return 2 nitrates
to the atmosphere.
-
There is too much irrigating and
nitrogen is leached beyond the root
systems of the plants. The nitrogen can
no longer be used by plants or
decomposers. Remove 2 nitrates from
your soil.
Fungi attack a corn crop and decompose
a crop that was meant for humans.
Add 2 nitrates to your soil.
A home gardener adds three times
the recommended amount of fertilizer
to a garden plot so the garden will grow
quicker. The plants die, but the soil
has lots of nitrates in it. Add 6 nitrates
to your soil.
A chemical spill kills all decomposers
in a particular area. Denitrifying
bacteria are quicker to return than
other decomposers. Return 2 nitrates
to the atmosphere.
A
38
Around and Around Nitrogen Goes Game Card
1
DETERMINING THE WINNER OF THE GAME
l
l
l
The farmer with the lowest number of nitrate particles did not have enough usable
nitrogen in the soil for a successful crop. Therefore, this farmer is not the winner.
The farmer with the most nitrate particles in his plot of soil added too much usable
nitrogen to the soil and did not get an optimum crop yield. The plants “burned” from
too much nitrogen being applied and the groundwater in the area contains a higher than
normal nitrate level. This farmer is not the winner of the game.
Of the remaining farmers, determine who has the most nitrate particles in the soil.
This farmer knows how to properly manage his/her land and is the winner of the game!
6. Discuss the outcome of the game. Was the game really faifl Do real farmers have more
control over their land than the farmers in the game do? Discuss what students learned
about the nitrogen cycle.
CONCLUSION
The nitrogen cycle is extremely important in agriculture and it is affected by many things.
Farmers must maintain their soil to be successful.
EXTENSIONS
1. After the game, give an oral quiz about information on the task cards. Reward students who
answer the questions correctly.
2. Make copies of the “Determining the Winner of the Games” procedure. Put then in envelopes
and have students open the envelope after they are done with the game.
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34
Name _---- ____ -~~---~~--~---_
RESULTS
Name of food
# of days
until first
changes
Changes seen
Gas production (did
bag puff up? odor?)
1.
2.
3.
4.
5.
6.
Draw the fungi in two bags you thought most interesting. (Label the food by name.)
c
L, Name of Food
Name of Food
CONCLUSION
1 . The most interesting decomposition I saw was
Why?
2. Were your results different from your predictions?How?
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31
decomposition (from previous experiment), or l/2 teaspoon of a fertilizer rich in
nitrogen. (To obtain juice from the decomposition bags, carefully punch one or two
holes in the bag and collect in a plastic cup.)
.
Examine both jars on a daily basis. Is there a change in growth in either bowl after one
week? After two weeks?
.
How do you explain the differences you see?
.
What would happen if products of decomposition from a compost pile, fertilizer or
products of a landfill got into a stream or reservoir?
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2. Obtain some leguminous plants (bean, pea, lupine, wild sweet pea or peanut) and some nonleguminous plants (grass or flowering plant such as marigold, pansy or tomato). Compare
the root stmcture of each plant. Have the students observe the nodules that contain
nitrogen-fixing bacteria on the legume roots. Have students draw a picture of each root that
they examine. Discuss the importance of nitrogen-fixing bacteria.
3. Observe fungi and bacteria under a microscope. Discuss their role in decomposition.
4. Have a competition to see who can get one piece of white bread to
has the most mold after two to three weeks.
the quickest or who
5. Have students research and draw the life cycle of one food product they decomposed (grape,
potato, etc.). Decomposition should be part of the cycle ! In the agricuttural production of
this food, do fungi play a negative role, i.e. cause plant disease?
A.
6. Have students sing or listen to the song “Decomposition” from the Banana Slug String Band.
7. Compare the decomposition process of white bread without preservatives to white bread
with preservatives.
8. Research the role of mushrooms, earthworms and people in the decomposition cycle.
9. Research the anatomy of fungi and mushrooms. If possible, view them under a microscope.
10. Obtain a large plastic bag of grass clippings. Place your hand in a smaller plastic bag and
then insert your covered hand into the bag. Repeat each day for several days. What do you
notice?
4
29
Fungi
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Fungi, such as molds and mushrooms, are one group of decomposers. Since fungi have no
chlorophyll, they cannot manufacture their own food. They get their food and their energy by
decomposing plant and animal matter. Fungi develop from tiny particles called spores. When
the spores settle in a proper environment, such as on bread, they grow and produce more
spores. These may travel in the air or stay in the ground and eventually land on the other
decaying material, to begin the life cycle again.
In this experiment several types of fungi may be visible on food. The black fungus is usually
Rh&opus. Orange or red fungus is called Neurospora. The blue-green fungus frequently found
on oranges is known as Penidllium. Aspergillus produces a black fungus and decomposes many
types of food.
Bacteria
Another set of decomposers is bacteria. Though some bacteria contain chlorophyll and can
produce their own food, most obtain their nutrition from their surroundings. The study of
bacteria is complex and will be studied by students when they learn more about specific cell
components.
By aiding in the decomposition of organic material, fungi and bacteria speed up cornposting and
the return of nutrients to the soil. The addition of organic material to the soil improves the
quality of the soil and helps aerate the soil.
Fungi and bacteria may also cause problems in agriculture. Many cause diseases in plants which
reduces crop yields. Fungi and bacteria can also attack seeds and prevent seed germination.
PROCEDURE
1 . Prepare the following:
l
l
.
l
Obtain one slice of bread for each student group.
Chop up different types of food so that each group will have at least six different foods to
observe, one of them being white bread.
Find a warm, dark location where students can store food.
Make a solution of dirty water by mixing 2 handfuls of fresh dirt (that looks like it
contains organic matter) with one gallon of water. Store in a 1 gallon plastic milk
carton until ready for use.
2. Ask your students the following questions. Have them write their thoughts down in a journal
or on a piece of paper and then discuss their thoughts with a partner.
l
Why do you think it is important to have fungi and bacteria in the environment?
l
What do you think would happen if all fungi and bacteria were destroyed?
.
What are some problems fungi and bacteria create?
Hopefully the students will mention many ideas, including the fact that fungi and bacteria
decompose things so that the finite amount of elements on our planet can be used again to
support life. It is important, at this point, to allow the students to express their thoughts
27
4
READING #3
THE ROCK/SOIL CYCLE
Imagine you are looking at a pile of soil. Think, for a minute, about how that soil was formed.
Some of the particles of dirt were once rock, others were parts of plants and animals, and some
are even tiny living creatures. You are about to learn a little more about the rock cycle and
about the soil particles that come from rocks.
ROCKS
The rock cycle is the slowest of all cycles. Igneous rock is formed during volcanic eruptions
as magma and lava cool and harden. Over time, the igneous rock is weathered by the sun, wind
and water to produce tiny dirt particles that become part of the soil. Eventually the pebbles and
soil are pressed together with the aid of water and form sedimentary rock. When
sedimentary rock or igneous rock are exposed to heat, chemicals or pressure, they become
metamorphic rock. Metamorphic rock and sedimentary rock may be pushed under the
Earth’s crust to reliquify into magma or lava and become igneous rock again. Metamorphic rock
can also break into little dirt particles that can be cemented together to form sedimentary rock.
Any of the three major types of rocks can form into the other types of rocks or can be broken
-
down into soil. Examine the rock cycle diagram to see how the rock cycle works.
THE ROCK CYCLE
I
MAGMA
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I
READING #2
THE WATER CYCLE
Imagine that you are on the moon looking down on Earth. What do you see? Most people imagine
a round planet, partially covered with white clouds and mostly blue in color. Both the white and
blue we envision are made of water droplets. Over 70% of the Earth’s surface is covered with
water. Let’s look at what happens to this water.
There is a constant movement of water from the ocean, to the air, to the land and back again to
the ocean. As the water is warmed by sunlight, it evaporates into the air as water vapor. Water
vapor-filled air is cooled when it is forced upward by mountains, hills or colder air. The water
vapor cools and condenses into droplets and forms clouds. Eventually the clouds can no longer
hold any more water vapor, and droplets (precipitation) fall to the Earth as rain, sleet, hail or
snow. Most of the precipitation falls into oceans. The precipitation that falls on the land is
absorbed into the ground; collects in rivers, lakes or streams; is utilized by plants and animals;
and eventually evaporates again.
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When people perspire and dogs pant, they are cooling themselves off by the process of
evaporation.
Plants also release water vapor into the air in a process called transpiration.
Water vapor is released from the leaves as the plants grow. Orchards and forests are not only
cooler because they prevent the ground below them from getting direct sunlight, but also
because they release cool water vapor into the air. The process of transpiration is extremely
important in maintaining a temperature on the Earth’s surface that is suitable for life.
As humans alter the Earth’s surface, the water cycle is also affected. As the challenge continues
to provide enough fresh water on Earth to meet the needs of living things, scientists continue to
seek ways of increasing the volume of fresh water and to use the fresh water available as
conservatively as possible. Some examples include drip irrigation systems on gardens and
farms, removing the salt from salt water (desalinization) and using water more than once
(reclamation).
Examine the water cycle diagram. Notice how water moves through the cycle.
22
Take a look at the carbon-oxygen cycle diagram. Notice how carbon dioxide and ox ygen flow
throughout the cycle. Think about how plants and animals depend on this cycle and on each 0th
Think of how your individual actions affect the carbon-oxygen cycle.
THINK ABOUT IT
*
What are three things you do that affect the carbon/oxygen cycle?
l
How do large forest or grass fires affect the carbon/oxygen cycle?
*
Suppose a farmer plants ten acres of walnut trees on desolate land. How does this affect the
carbon/oxygen cycle?
t
How do cutting down a forest and building houses affect the carbon/oxygen cycle?
*
How do cutting down trees and then replanting them affect the carbon/oxygen cycle?
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20
THE NITROGEN CYCLE
legumes
I
Nitrate
b3$Foya %
nitrogen
fertilizer
Nitrite
bacteria
in soil
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NITROGEN AND THE NITROGEN CYCLE
Take a deep breath! What did you just inhale ? If you thought “air”, you are right! Air is made
of many types of particles. We most often think of air as oxygen (OJ, but the Earth’s “air”,
better known as the atmosphere, is 78% nitrogen gas (NJ and only about 21% oxygen gas. The
Earth’s atmosphere is one of the many things that makes our planet so unique. Living organisms
depend on the Earth’s atmosphere for survival. In this reading, you will learn how plants and
animals depend on nitrogen for survival.
In every acre of land (about the size of a football field) there are about 35,000 tons of nitrogen
particles. This is the weight of about 18 elephants ! Nitrogen is important for plant and animal
growth. It is one of many elements needed to build proteins which form muscles in animals. It
is also important in forming enzymes needed for animals to digest food. Nitrogen is one of the
elements the unique chemical chlorophyll which allows plants to capture energy from the sun
and make food for themselves. Nitrogen is an extremely important chemical and life would not
exist if plants and animals did not have it available to them.
Take a look at the diagram of the nitrogen cycle. Notice how complex it is and how nitrogen flows
through the cycle.
Nitrogen exists in many forms. The most abundant form is nitrogen gas (N2). Plants and
animals cannot use nitrogen gas. They must absorb nitrogen as an element in other compounds.
Nitrogen can exist in many forms which are usable by plants including nitrates (NO;),
nitrites
(NO;), ammonium (NH,+) and ammonia (NH& Locate the different compounds on the nitrogen
cycle diagram.
NITROGEN FIXATION
The process of changing nitrogen gas into nitrogen usable by plants is called nitrogen
fixation. Nitrogen gas can be hit by lightning to become nitrates, a compound that plants can
use, but most often nitrogen gas is converted to usable nitrogen by nitrogen-fixing bacteria or
by laboratory chemical processes.
Nitrogen-fixing bacteria naturally exist in soil and water.
convert nitrogen gas to nitrates which plants can use.
As part of their life processes, they
Some nitrogen-fixing bacteria, called
Rhizobia , live within the root structures of certain plants called legumes. The special root
structures in which they live are called nodules. Farmers often plant legumes such as beans,
alfalfa and peas to replenish the usable nitrogen in the soil. The plant remains are turned into
16
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-
-
cl Assign each group member a number --
1, 2 or 3. The l’s will read “Reading #l”, the
-
2’s will read “Reading #2” and the 3’s will read “Reading #3.” Before the students
read their assigned reading, have them complete the top section of the
“Starting ‘All Over Again” worksheet.
d)
After the students have finished reading the material, have all of the l’s meet and
discuss what they read. At the same time, have the 2’s and 3’s become experts on their
readings. Each group of “experts” will discuss what they learned and then complete the
second half of the “Starting All Over Again” worksheet.
e)
Have the original groups meet again and each “expert” will explain to the rest of the
group the general idea of his reading and some important key points. This allows all
students to learn general concepts about the three cycles without having to read about all
of them.
f)
Provide time for the groups to discuss the “Think About It” section of the readings and/or
require students to write about some of the questions as homework.
5. In a whole class setting, using the transparencies on each cycle, summarize the major
findings of each group. Emphasize how the production of food and fiber affects each of these
cycles.
.
If necessary, each studentcan be given a paper copy of the cycle transparencies.
.
If appropriate, students can be asked to take notes on these cycles in their lab notebooks
or journals.
CONCLUSION
Unless materials are used over and over again, living things cannot survive. There are
many cycles in nature. Energy must be transferred or utilized if the cycles of matter are to
occur.
VARIATIONS
1 .
Have all the students read each of the readings over a longer period of time.
2. Design “reading station” assignments that your students must complete over a certain
time period. Have a separate reading at each station with discussion questions your
students must complete.
EXTENSIONS
1 . Try raising a green water plant such as Anacharis or Elodea with a snail in a closed jar
or test tube. At the time of set-up, the plant should be covered with water, there should
be an air space and the jar should be covered. Be sure the system is in a well lit area and
that the water does not get too hot. Discuss how each organism beneffis the other.
2. Biospheres 1 and ll were attempts to make self-sufficient ecosystems. Have students
research the results of Biosphere I and find out the status of Biosphere II. Are these
self-sustaining ecosystems?
3. There are many excellent experiments that will enable students to understand the water
cycle and the connection between evaporation and condensation. Consult science
textbooks or the Water Education Foundation for water cycle activities.
13
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READ ALL ABOUT IT!
(A Cycles Reading Assignment)
PURPOSE
The purpose of this activity is for students to gain background knowledge on the basic cycles of
nature and to begin to understand where agriculture fits into the “cycle picture.”
CONCEPTS
There are natural cycles that provide nutrients and necessary elements for plant and animal
survival.
There is a constant exchange and recycling of materials between air, soil, water, plants and
animals. If these materials were used only once, they would soon run out?
Carbon and oxygen constantly circulate through living things, soil, water and air.
Only a small portion of the Earth’s water is available for plants and animals. The water
cycle provides fresh water for the use of living things4
The slow process of the rock cycle eventually contributes to soil composition.5
The nitrogen cycle is a complex process of exchange of nitrogen compounds throughout living
and non-living things. The constant presence of the various forms of nitrogen operating in
the nitrogen cycle are important for the growth of plants and animals.3
-
MATERIALS
For Each Student:
l
.
The “Nitrogen and Nitrogen Cycle” reading assignment
1 copy of “Starting All Over Again” titled “The Nitrogen Cycle”
For Each Team of 3:
.
.
.
.
1 copy of “The Carbon/Oxygen Cycle” reading assignment’
1 copy of “Water Cycle” reading assignment
1 copy of “Rock/Soil Cycle” reading assignment
3 copies of “Starting All Over Again” worksheet
BACKGROUND INFORMATION
As plants develop and grow, they need essential nutrients and utilize various components of
the carbon/oxygen cycle, water cycle, rock/soil cycle and nitrogen cycle. More information
and lessons on the specific nutrients plants require are available in the unit “How Much Is
Too Much? How Little Is Too Little?” which is available from the California Foundation for
Agriculture in the Classroom (see Teacher Resources at the end of this unit).
Through the following readings, students will learn about various cycles and determine how
plants and animals, including humans, are a part of them. Encourage your students to think
how growing crops and raising animals affect specific cycles. You might choose to do this
lesson while you are waiting for experimental results from the “Rotting World” laboratory
included in this packet.
11
*
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clean, dry sock
remove water
add heat
dirty sock
clean, wet sock
remove soap,
water, and dirt
d.
soapy, wet,
somewhat clean
sock
Using the sock model, discuss the following:
l
Energy must be added to the cycle in order for it to operate.
4
l
l
e.
One cycles may affect other cycles.
Matter from other cycles is often added and/or removed from the cycle being
analyzed. For example, soap and water are added and removed from the sock cycle.
Mud is removed from one part of the sock cycle and put in at another part of the sock
cycle.
A general model for cycles is shown below:
ADD OR REMOVE
SOMETHING
MAlTER
2. Have students form cooperative groups of 3-4 students. Pass out scratch paper to each
group.
a Have groups braiWStorm other examples of cycles in the environment. If necessary,
brainstorm a few ideas as a class before breaking into groups. Some suggestions for
cycles are described in the following list.
9
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UNIT OVERVIEW
BRIEF DESCRIPTION
Through a series of activities and experiments, students will learn the importance of cycles in
nature, how they relate to the production of food and fiber, and how life on planet Earth is
dependent on cycles. Students review the concept of a “cycle” by looking at a simple model and
transfer this knowledge to the carbon/oxygen, water, rock/soil and nitrogen cycles. The
nitrogen cycle is examined in depth since it is closely connected to agriculture production. At
the end of the unit, students integrate their agricultural-ecology knowledge with language arts
and social sciences by participating in a nitrogen game and acting out the “nitrogen cycle” in a
role-play.
SCIENCE THEMES
l
l
Systems and Interactions
Stability
.
.
Patterns of Change
Energy
CONCEPTS
(Footnotes refer to specific pages in the Science Framework for California Public Schools. See
page 52.)
.
Energy and matter are transferred among organisms within each ecosystem.’
.
Matter needed to sustain life is cycled and recycled within an ecosystem.
.
Over 30 chemical elements are required for life. Plants require 17 specific chemical
elements. During life, plants and animals utilize these chemicals. When the organisms die,
these chemicals are returned to the environment (the air, soil and water) and are available
for reuse by other organisms.2
.
All living things are connected to the non-living part of ecosystems by their need for
chemicals.
.
The use and reuse of materials forms a cycle as matter flows from the non-living part of the
environment to living things and back again?
.
Energy flows into and out of cycles at various stages. Many of the reactions that occur in the
cycle require energy input from sunlight, heat or stored chemical energy.
.
The water cycle sustains the Earth’s land life by supplying it with fresh water.4
.
Soils are part of the rock cycle because they are formed from the breakdown of rack and may
form into rock again?
.
In natural cycles, a series of steps “recycle” the materials in the environment. If recycling
did not occur, life on Earth would eventually disappear.
.
Human activities affect the balance of nutrient cycles. Humans must exercise judgment,
care and planning in their use of natural resources so that well balanced ecosystems can be
maintained! q
Curriculum Advisory
and Review Committee
Lois Andre Bechely
Educational Consultant/Former
Teacher
Los Angeles Unified School
District
Los Angeles, CA
Clark Biggs
Information Director
California Farm Bureau
Federation
Sacramento, CA
Joanne Borovoy
Kindergarten Teacher
John B. Reibli School
Mark West Union School District
Santa Rosa, CA
Francine Bradley, Ph.D.
Cooperative Extension Avian
Sciences Specialist
University of California
Davis, CA
Beth Brookhart
Freelance Journalist
Bakersfield, CA
Barbara Buck
Executive Vice President
Fresh Produce and Floral Council
Los Angeles, CA
Lucas Calpouzos, Ph.D.
Former Dean of Agriculture
California State University
Chico, CA
Debbie Calvo
Executive Director
Alliance for Food and Fiber
Los Angeles, CA
David Chaney
Information Analyst
UC Sustainable Agriculture
Research and Education Program
University of Caltfornia
Davis, CA
Jerry Delsol
Agriscience Teacher
Douglass Junior High School
Woodland Joint Unified Schod
District
Woodland, CA
Pamela Emery
Curriculum Coordinator
California Foundation for
Agriculture in the Classroom
Sacramento, CA
Richard Engel
Agriscience Teacher
Woodland Senior High School
Woodland Joint Unified School
District
Woodland, CA
J a c q u e s Franc0
Program Coordinator
California Department of Food
and Agriculture
Fertilizer Research and
Education Program
Sacramento, CA
David Hammond
Lead Consultant
California Department of
Education
Science and Environmental
Science Unit
Sacramento, CA
C a r o l y n Hayworth
Manager, Investor and Public
Relations
Calgene, Inc.
Davis, CA
Karen Holtman
Kindergarten Teacher
John B. Reibli School
Mark West Union School District
Santa Rosa, CA
Wendy Jenks
Director of Programs
California Fertilizer Association
Sacramento, CA
C a r r i e LaLonde
Operations Manager
Valley Fruit and Produce Council
Los Angdes, CA
Jean Landeen
Agricultural Education
Consultant
California Department of
Education
Agricultural Education
Sacramento, CA
Mark Linder
President
California Foundation for
Agriculture in the Classroom
Sacramento, CA
Cynthia Livingston
ESL Teacher Specialist
Marshall Elementary School
Glendale Unified School District
Glendale, CA
Al Ludwick
Western Director
Potash and Phosphate Institute
Mill Valley, CA
Holiday Matchett
Elementary Science Teacher
Dingle Elementary School
Woodland Joint Unified School
District
Woodland, CA
C r a i g McNamara
Farmer
Sierra Orchards
W inters, CA
Donna Mitten
Director, Product Planning
Calgene, Inc.
Davis, CA
Jean Kennedy
Agriscience Teacher
Armijo High School
Fairfield-Suisun Unified School
District
Fairfield, CA
Robyn Moore
Elementary School Teacher
Presentation Elementary School
Sacramento County
Sacramento, CA
Kelly King
Teacher Speclallst
Glenoaks Elementary School
Glendale Unified School District
Glendale, CA
Michael M o o r e s
Biology Teacher
Yuba City Hugh School
Yuba City Unrfied School Dtstrlct
Yuba City, CA
3
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