Primary Type: Lesson Plan
Status: Published
This is a resource from CPALMS (www.cpalms.org) where all educators go for bright ideas!
Resource ID#: 75928
Law of Conservation of Mass and Living Systems
The students will explore using open and closed systems can be used to explain the Law of Conservation of Mass. The students will also observe a
chemical reaction to determine if mass is conserved. The student will also perform research to understand that living systems follow the Law of
Conservation of Mass.
Subject(s): Science
Grade Level(s): 8
Intended Audience: Educators
Suggested Technology: Computer for Presenter,
Interactive Whiteboard, LCD Projector
Instructional Time: 1 Hour(s) 50 Minute(s)
Resource supports reading in content area: Yes
Freely Available: Yes
Keywords: law of conservations of mass, closed system, open system, photosynthesis, respiration, carbon cycle
Resource Collection: FCR-STEMLearn Cell Biology
LESSON CONTENT
Lesson Plan Template: Learning Cycle (5E Model)
Learning Objectives: What will students know and be able to do as a result of this lesson?
The students will explain the law of conservation of mass.
The student will demonstrate and explain that living systems obey the the law of conservation of mass.
Prior Knowledge: What prior knowledge should students have for this lesson?
The student should understand that photosynthesis produces the oxygen needed for cellular respiration
The students should understand that the carbon cycle involves matter and energy continously being transferred between organisms and the physical environment.
The students should understand cellular respiration involves breaking down food to provide energy and release carbon dioxide.
The student should understand mass is the amount of "stuff" inside and object.
The student should understand energy is the ability to cause a change or work..
The student should understand that an open system allows input and output into the system.
The student should understand that a closed system does not allow inputs or outputs.
Guiding Questions: What are the guiding questions for this lesson?
How is mass conserved in living systems?
Answer:Mass is conserved in living systems through the processes of photosynthesis, cellular respiration, and the carbon cycle.
How can it be demonstrated that mass is conserved in living systems?
Answer:It can be demonstrated in photosynthesis through the process of plants taking in light energy and carbon dioxide and producing oxygen. It is demonstrated in
cellular respiration through the process of braking down food to provide energy and releasing carbon dioxide. During the carbon cycle matter and energy are
continuously transferred within and between organisms and their physical environment.
Engage: What object, event, or questions will the teacher use to trigger the students' curiosity and engage them in the concepts?
Quick demo: Materials: Hot plate, two beakers, bags of ice, hot gloves, digital balance
page 1 of 4 a)Teacher takes a scoop of ice and measures the mass in grams (g) using a scale. The teacher should make sure that she TARE the scoop before adding the ice and
placing on a balance. A digital scale is TARED when an object is placed on the balance and then the tare button is touched to display the mass as zero. An example
would be a beaker placed on the scale. The tare button is touched, as a result, anything placed in the beaker afterwards will display the mass of the contents only.
b)The teacher then places the ice in a beaker, and melts it on a hot plate. The teacher should then TARE another beaker on a digital scale. The melted ice is then
added to the TARED beaker. The teacher will observe the mass and display the mass in grams (g) with the correct unit of measurement onto the smart board. If a
smart board is not available, teacher should use dry erase markers to display the mass on the blackboard. The students are to record the data in their science
interactive notebooks.
c) The teacher takes the melted ice from the beaker and places it on a hot plate. The teacher will leave the beaker on the hot plate until the liquid begins to boil. Once
the liquid begins to boil, the teacher carefully removes, with a heat resistant glove, the beaker from the hot plate and pours the liquid into a TARED beaker. The mass
(g) of the liquid is taken. The mass from the hot liquid is once again displayed for the students to record the data in their science interactive notebooks. It should be
displayed with the correct unit of measurement, grams(g).
d) Teacher repeats steps a-c but in a closed system (place a lid on top of the beaker). The difference between the open and closed system will be the covering of the
beakers.
During the demo, the teacher will explain to the students that everything that is measured is considered to be part of the "system". Example, the beaker and the liquid
would be a system. The beaker, the liquid and the lid would also be a complete system.
Once the demonstration is complete, the teacher will display the results on a table to represent the Law of Conservation of Mass. At this point, the teacher will only
ask questions about the data. She will not elaborate. The teacher will explain to the students the law of conservation of mass. The Law of Conservation of Mass is
demonstrated with the data. The data collected from the covered beaker will be data collected from a closed system. The data collected from the beaker with out a
cover, is data collected from an open system. The students will observe from the data that in a closed system mass is conserved. In an open system mass is not
conserved.
The students will watch the following video, Antoine Lavoisier. The students should take notes over the video in their science interactive notebook.
Explore: What will the students do to explore the concepts and skills being developed through the lesson?
Teacher Demonstration
A Ziploc bag containing 2 beakers, one containing 100 mL of vinegar and the other 15 grams of baking soda, will be displayed before the class.
a) Students will use their science interactive notebooks to record predictions, with an explanation as to why they made their prediction, about the total mass of the
bag and its contents. At this point, students should also make sketches in their science notebook of the set up.
b) Students will record, in their science interactive notebooks, another prediction about the total mass of the system after the contents are combined. This
information should also be recorded in their science interactive notebooks.
c) Teacher will measure the mass of the system and display data for the students on the Smartboard. If a Smartboard is unavailable, the teacher will write the
mass, using correct units of measurements grams (g) onto the blackboard. The system is the Ziplock bag, 2 beakers, vinegar, and baking soda.
d) Students will record the data the teacher displays on the Smartboard in their science interactive notebook. The data is the measurements of mass the teacher
collected in step c.
e) Teacher will combine the contents of the bag. The teacher will then measure the mass of the system again, after the release of energy is complete. The release
of energy is complete when there are no more bubbles being released inside of the Ziploc bag. The data should once again be displayed on the Smartboard for the
students to record in their science interactive notebooks.
f)The students will compare the results with their predictions. The students will revise their knowledge by recording an explanation in their science interactive
notebooks stating if their predictions were correct or incorrect based on the data the students recorded from the demonstration. The students will share their
explanation with an elbow partner. The students must explain to their elbow partner if their predictions were correct or not and give the explanation for their
response. The teacher will call upon different students to share their responses with the class.
The choice of students will be based upon teacher observations from circulating and observing students completing the task of comparing their predictions to the data
collected from the vinegar and baking soda demonstration.
The teacher will ask the students,
"What does the words "mass is conserved" mean?" Answer: It means that beginning mass and ending mass are the same
"Was mass conserved in this demonstration?" Answer: Yes, this is a closed system and nothing was allow to leave or enter the system,
"What is the evidence that mass was conserved?" Answer: The amount of everything at the beginning and end are same.
After discussions about the data is complete, the teacher will remind the students that this is an example of the Law of Conservation of Mass. The Law of Conservation
of Mass states that mass is not created or destroyed it only changes form. The law also states that in a closed system mass is conserved.
The teacher will ask the students if there are any living systems in nature that follow the Law of Conservation of Mass. If there are no acceptable responses, the
teacher may ask students, "How did you get to school?" "How were you able to get up?" "What did you eat?" "Where did the food come from?" These questions will
lead to a discussion of photosynthesis, respiration, and the carbon cycle. Explain to the students how these systems represent the Law of Conservation of Mass.
Use the following equations to assist you.
Photosynthesis: 6CO2 + 6H2O + Energy C6 H12 06 + 6O2 OR
Cellular Respiration: C6 H12 06 + 6O2
6CO2 + 6H2O OR
Carbon Dioxide + Water + Energy
Glucose + Oxygen
Glucose + Oxygen
Carbon Dioxide + Oxygen
Explain: What will the students and teacher do so students have opportunities to clarify their ideas, reach a conclusion or
generalization, and communicate what they know to others?
The students will answer the following questions. Instruct students to use the data collected, from the ice demonstration, to assisted them
Student Handout
1. State the Law of Conservation of Mass.
2. Complete the table with the data collected from the lab demonstration observations. The table should contain the before and after data?
3. How does it relate to the law of conservation of mass? Conservation of Mass Assessment Formative Assessment with answers.docx
Elaborate: What will the students do to apply their conceptual understanding and skills to solve a problem, make a decision,
page 2 of 4 perform a task, or make sense of new knowledge?
The students will read the following article: The Law of Conservation of Mass
The students will create Cornell Notes while reading the article. The Cornell Notes will include a summary. Cornell Notes directions
After reading the article and creating Cornell Notes: Make a list of the things you have learned from the article. Use an example in the article to cite evidence for the
Law of Conservation of Mass.
Exit slip: If a piece of wood starts to burn, is the mass conserved? Explain why.
Summative Assessment
The summary of the article, The Law of Conservation of Mass, will be used to determine if the students have made the connection between Law of Conservation of
Mass and living systems.
Exit slip. The exit slip will be used to show that students understand the conservation of mass.Exit slip: If a piece of wood starts to burn, is the mass conserved?
Explain why.
Formative Assessment
Teacher will use interactive notebooks to check for understanding when students are making predictions and providing explanation. Website for how to implement
Science Interactive Notebooks
Student handout will be used to check for understanding. Conservation of Mass Assessment Formative Assessment.docx
Feedback to Students
The teacher will provide feedback as follows:
The teacher will circulate around the room and observe the students complete their tasks and provide verbal feedback.
Teacher praises students whose interactive notebook demonstrates understanding of links involving mass.
Teacher can ask students to provide complete diagrams for future reference.
During the activities the teacher will conduct interviews to track progress.
Students will be asked probing questions to guide them in making connections.
Example questions:
Would you consider the demo as observed an open or closed system?
What makes it a open system?
What makes it a closed system?
How does open and closed systems relate to the law of conservation of mass.
Can you give an example of a living system that demonstrates the law of conservation of mass?
Have students justify their responses to the previous questions.
ACCOMMODATIONS & RECOMMENDATIONS
Accommodations:
In the Explore section of the lesson, the teacher can provide a completed table for students who are ELL or ESE. The table will contain the data from the
demonstrations.Ice Data Table.docx
The Elaborate section of the lesson requires students to take Cornell Notes while reading the passage The Law of Conservation of Mass, The video Antoine Lavoisier
may also be used to support students who have are having difficulty comprehending the article.
Extensions:
For Gifted or Honor Students: The students will create an illustration or diagram of the carbon cycle.
Requirements for illustration/diagram: The illustration must show the Law of Conservation of Mass.It must demonstrate that there is a continuous exchange of matter
and energy between organisms and their physical environment.
Suggested Technology: Computer for Presenter, Interactive Whiteboard, LCD Projector
Special Materials Needed:
Hot plate
beakers
ice
gloves
vinegar
baking soda
ziploc bags
digital scale
Further Recommendations:
If students indicate understanding, as shown through the summative and formative assessments, it is recommended that the teacher proceed directly to the Law of
Conservation of Energy.
page 3 of 4 Additional Information/Instructions
By Author/Submitter
This resource addresses only the Law of Conservation of Mass. The Law of Conservation of Energy is not addressed.
SOURCE AND ACCESS INFORMATION
Contributed by: Lisa Brown
Name of Author/Source: Lisa Brown
District/Organization of Contributor(s): Orange
Is this Resource freely Available? Yes
Access Privileges: Public
License: CPALMS License - no distribution - non commercial
Related Standards
Name
SC.8.L.18.4:
Description
Cite evidence that living systems follow the Laws of Conservation of Mass and Energy.
page 4 of 4