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The Arizona STEM Acceleration Project

Ecosystem Sealed for 50 Years

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Ecosystem Sealed for 50 Years

A 6th and 7th grade STEM lesson

Author: Christine Mendoza

Date: 5/3/24

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Notes for teachers

CO2 monitors can be purchased from Amazon.

Sensors can also be purchased from Vernier.

Go Direct CO2 Gas Sensor

List of Materials

Computers or other devices with internet access
Chart paper or large whiteboards and markers
C02 monitor or CO2 sensor
Hydroponic grow lamp
Aluminum foil
Gallon size Ziploc bag
Spinach

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Standards

Arizona Science Standards

7.L2U1.12 Construct an explanation for how some plant cells convert light energy into food energy.

6.L2U1.14 Construct a model that shows the cycling of matter and flow of energy in ecosystems.

Standards

Arizona Technology Standards

Standard 3. Knowledge Constructor - Students critically curate a variety of resources using digital tools to construct knowledge, produce creative artifacts, and make meaningful learning experiences for themselves and others

6-8.3.d. Students explore real world problems and issues and actively pursue solutions for them.

This lesson contains an opportunity to design and build an ecosystem in a bottle as an extension activity. If used, this activity could also incorporate engineering standards.

Arizona Engineering Technical Standards:

STANDARD 2.0 CREATE ENGINEERING SOLUTIONS BY APPLYING A STRUCTURED PROBLEM-SOLVING/DECISION MAKING PROCESS

2.1 Identify the problem

2.2 Develop a problem statement based on facts, research, and experience

2.3 Explore possible issues or options to the problem

2.4 Select the best solution within the constraints and criteria

2.5 Develop a prototype or model to test the selected solution

2.6 Implement the solution

2.7 Evaluate the solution, and revise or repeat if necessary (i.e., Are there other solutions, better solutions, or cheaper solutions? etc.)

2.8 Document and report all results

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Objectives:

The students will develop a model to show the cycling of matter and the process of photosynthesis.
The students will gather information through experiments, simulations and research to revise their model and construct an explanation.
The students will construct an explanation of the ecosystem that has been sealed for over 50 years.

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Agenda (Approximately 2 Weeks)

Introduce Phenomenon: 1-2 class periods

Measuring CO2 and Humidity in a Closed System: 1 class period

Research: 1 class period

Investigate (Simulation): 1-2 class periods

Revise Model: 1 class period

Revisit Phenomenon: 1 class period

Assessment: 1 class period

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Phenomenon: Ecosystem Sealed for Over 50 Years

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Initial Model: What do plants need in order to survive?

Develop an initial model to show what pants need in order to survive.

Include all possible inputs and outputs to the system.

The purpose of this initial model is to assess students background knowledge about the inputs and outputs associated with photosynthesis.

Students at this grade level should have background knowledge about water and sunlight as inputs for the plant. They should also have some prior knowledge about air being an input, but their may be some misconceptions or debate related to CO2 and O2, and whether they are inputs, outputs, or both.

Have students begin working independently to create an initial model in their science notebooks. Then have students work in partners to share their models and record similarities and differences. Finally, draw from students similarities and differences lists to develop an initial class model.

After completing the class consensus model, have students work together to create a driving question board. Begin by having students record questions that came up during the creation of the model, and questions they had on their wonder chart about the phenomenon. Since there is generally some kind of question around CO2 and O2, these questions can be used to drive the next investigation.

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Measuring CO2 and Humidity in a Closed System

Materials:

10-12 spinach leaves
1 gallon plastic bag
aluminum foil
CO2 monitor or CO2 sensor
hydroponic grow lamp

Hands-On Activity: This activity can be done as a whole class or in smaller groups depending on the amount of materials.

Hands-On Activity Procedure:

Open the gallon size bag and move it to fill it with air.
Place the CO2 sensor in the bag and seal it shut
Place the bag directly under the hydroponic grow lamp and wait for 5 minutes to allow the system to stabilize.
Create an aluminum foil tray by folding a piece of foil in half. The foil should fit inside the gallon bag.
Place the spinach leaves on the foil so that they do not overlap.
After 5 minutes record the initial CO2 and humidity readings.
Place the foil tray with the spinach leaves inside the bag. Make sure to do this quickly. You do not want to have the bag open for too long.
Wait 10 minutes. Then record the CO2 and humidity readings inside the bag.
If time permits, you may wish to wait another 10 minutes and then take a second reading.
Have students work with a partner to analyze the results and draw conclusions.

Teacher notes: Over time, students should see a decrease in carbon dioxide levels and an increase in humidity levels. They may even see condensation forming on the inside of the bag. Students should draw the conclusion that the leaves are taking in CO2 and releasing water vapor.

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Research:

How do CO2, O2, and water vapor enter and exit through the leaf?

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Investigate:

What is going on inside the plant?

Investigate using the Chloroplasts and Food Simulation.

This investigation will require a device with internet access. Students may work independently, in partners, or in small groups depending on the number of devices available. The teacher could also run the investigation as a whole class demo if needed.

Have students use the Chloroplasts and Food Simulation from OpenSciEd to investigate what is happening inside the plant.

Begin by having the students run the simulation and make observations with the pre programmed settings.

Students should observe the inputs into the chloroplasts, the changes occurring within the chloroplasts, and the outputs from the chloroplast.
Before moving onto the next step, the teacher may wish to have students share their noticings and wonderings as a whole class.

Have the students conduct mini experiments by changing one of the variables on the simulation at a time.

What happens when you increase or decrease the number of chloroplasts?
What happens when you increase or decrease the amount of carbon dioxide?
What happens when you increase or decrease the amount of water?
What happens when you increase or decrease the amount light?

Have students create posters or whiteboards to share out their findings.

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Revise Initial Model: What do plants need in order to survive?

Use the information you have gathered from your investigations and research to revise your initial model.

The purpose of this revised model is for students to synthesize their learning. Revised models should now show light, CO2, and water as inputs. Models should include the stomata and chloroplasts, and they should show O2 and sugar as outputs. Depending on students understanding of chemical reactions, models could also include the equation for photosynthesis.

Have students begin working independently to create their revised model in their science notebooks. Then have students work in partners to share their models and record similarities and differences. Finally, draw from students similarities and differences lists to develop an initial class model, or in lieu of a class model, you can have students submit their final model as an assessment.

After creating the revised models, have students revisit their driving question boards. What questions have they been able to answer? What questions do they still have?

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Revisit Phenomenon

What can we now explain about the phenomenon?
What questions do we still have about the phenomenon?

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Assessment

Construct an explanation for the Ecosphere in a Bottle.

How has the plant been able to survive inside the sealed bottle for over 50 years?

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Differentiation

For students who are struggling, you may wish to incorporate some YouTube videos to help summarize the process of photosynthesis.

Photosynthesis for Kids

Photosynthesis in the Cycling of Matter

Remediation

Extension/Enrichment

As an extension, students can build their own terrarium in a bottle.

Terrariums: A Look at the Living and Nonliving World

How to Make a Soda Bottle Terrarium