How to Teach Respiration

Teaching cellular respiration can be difficult because students often do not understand molecules that they cannot see. While a basic understanding that animals breathe in oxygen and breathe out carbon dioxide is likely there for your students, proving this process through quantifiable measurements provides a much deeper understanding for most students. By employing oxygen and carbon dioxide sensors, like those available from Vernier, this process can become quantifiable and more enjoyable for your students.

Difficulty: Moderately Challenging

Instructions

Things You'll Need:

• Vernier carbon dioxide sensor
• Vernier oxygen sensor
• Vernier lab quest
• Biochamber 250 bottle

Respiration Experiment

1. Connect the oxygen and carbon dioxide sensors to your Lab Quest. The sensors will be immediately recognized and ready to take readings.

2. Insert the oxygen sensor into the Biochamber 250 in the back port. Have a student exhale into a bottle and insert the carbon dioxide sensor into the bottle opening. Click "enter" on your lab quest to begin taking readings.

3. Create a bar graph that shows the carbon dioxide level in the air versus the carbon dioxide level in the student's exhalation. Create another bar graph comparing the oxygen level in the air versus in the student's exhalation. On the x-axis you can plot time and on the y-axis plot the concentration of oxygen.

4. Create variables to extend the experiment. Have the student hold his or her breath for increasingly longer periods of time and measure the carbon dioxide and oxygen contents of the exhalation. Graph this data to show to the students that carbon dioxide levels will increase the longer the breath is held.

Tips & Warnings

• Try repeating the experiment with students of differing height, sex, and athletic fitness to see how each body differs. There are other oxygen and carbon dioxide sensors, such as the Pasport, that will perform similar functions. Refer to your owner's manual for information on operating your sensors, and run the experiment the same way detailed here.
• When you take the carbon dioxide sensor out of the bottle and insert the oxygen sensor, do this as quickly as possible to prevent contamination of the bottle's air supply.

References

• Vernier Carbon Dioxide Sensor
• Vernier Oxygen Sensor
• Vernier Sample collection bottles that fit the sensors

Resources

• Pasport Sensor

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