In this fun lesson plan, students will measure how the amount of carbon dioxide in their exhaled breath changes with exercise levels. Carbon dioxide is a product of cellular respiration, so the lesson highlights how breathing is connected to cellular respiration and energy production in our body. They will make the measurements using a simple colorimetric test and a phone with Google's Science Journal app.
This lesson helps students prepare for these Next Generation Science Standards
- MS-LS1-7. Develop a model to describe how food is rearranged through chemical reactions forming new molecules that support growth and/or release energy as this matter moves through an organism.
This lesson focuses on these aspects of NGSS Three Dimensional Learning:
|Science & Engineering Practices
||Disciplinary Core Ideas
|Planning and Carrying Out Investigations.
Collect data about the performance of a proposed object, tool, process, or system under a range of conditions.
Asking Questions and Defining Problems.
Ask questions that can be investigated within the scope of the classroom, outdoor environment, and museums and other public facilities with available resources and, when appropriate, frame a hypothesis based on observations and scientific principles.
Analyzing and Interpreting Data.
Analyze and interpret data to provide evidence for phenomena.
Constructing Explanations and Designing Solutions.
Apply scientific reasoning to show why the data or evidence is adequate for the explanation or conclusion.
|LS1.C: Organization for Matter and Energy Flow in Organisms.
Within individual organisms, food moves through a series of chemical reactions in which it is broken down and rearranged to form new molecules, to support growth, or to release energy.
PS3.D: Energy in Chemical Processes and Everyday Life.
Cellular respiration in plants and animals involve chemical reactions with oxygen that release stored energy. In these processes, complex molecules containing carbon react with oxygen to produce carbon dioxide and other materials.
|Energy and Matter.
Matter is conserved because atoms are conserved in physical and chemical processes.
Within a natural or designed system, the transfer of energy drives the motion and/or cycling of matter.
Cause and Effect.
Cause and effect relationships may be used to predict phenomena in natural or designed systems.
Systems and System Models.
Models can be used to represent systems and their interactions—such as inputs, processes and outputs—and energy, matter, and information flows within systems.
Svenja Lohner, PhD, Science Buddies
Materials per group of 2–4 students:
- Straws (2 per student)
- Check valves for straw (minimum 1 per group, can be re-used); available from
- 9 oz transparent cup or 150 mL beaker
- Rubber band
- Plastic wrap
- Bromothymol blue indicator solution (0.04%), available from Amazon
- Deionized, or distilled water; available at grocery stores
- Smartphone or tablet with Google's Science Journal app, available for free on Google Play for Android devices (version 4.4 or newer) or from the App Store for iOS devices (iOS 9.3 or newer).
Note: This project was tested with the Android version of Science Journal in which light intensity is measured using the ambient light sensor and given in lux. The iOS version uses the phone's camera to measure brightness resulting in data expressed in EV (Exposure Value). Lux values and Exposure Values are not the same. Whereas Exposure Value is a base-2 logarithmic scale, the lux scale is linear. This might affect your data and result in different values and graphs when you are using an iOS version of the app—both versions will work for this project though. The graph examples given in the procedure show light intensity in lux.
- Box or books to lean the phone against
Materials for teacher demonstration:
- 9 oz transparent cups or 150 mL beakers (5)
- Baking soda
- Distilled vinegar
- All of the materials listed for one student group
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this lesson plan.
Human Biology & Health
Cellular respiration, Energy, Breathing
- Understand the purpose and mechanism of cellular respiration
- Determine the relationship between breathing (respiration) and cellular respiration
- Analyze graphs of experimentally-recorded data