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Human Energy Systems | Activity 4.3

Activity 4.3: Carbon Movement (40 min)

Students examine the Carbon Movement question and discuss how the balance between photosynthesis and cellular respiration impact the exchange of carbon between the organic biomass pool and the inorganic atmosphere pool.

Resources Provided


Print the 4.3 Carbon Flux Scenario Cards. You will need to cut these apart before class. You may want to laminate them first in order to make them last longer. Print one copy of 4.3 Carbon Fluxes Worksheet for each student. Prepare a computer and projector to display the 4.3 Carbon Fluxes PPT.


1. Recall the Keeling Curve and identify the seasonal cycle.

Ask students to verbally share accounts of the Keeling Curve to activate their prior knowledge from lesson 3.

  • Display slide 2 of 4.3 Carbon Fluxes PPT, which shows an image of the Keeling Curve.
  • Ask the students about the “seasonal” cycle.
  • Have students think about and share their ideas that they wrote in Activity 4.1 about why the concentration of carbon dioxide in the atmosphere goes up in the winter and down in the summer each year.


Check to see if students are making the connection that photosynthesis causes the inorganic pool to shrink and the organic pool to grow, whereas cellular respiration causes the opposite trend. Students might also suggest that photosynthesis causes a “flux” to the biomass pool, and cellular respiration causes a “flux” to the atmosphere pool.


Demonstrate how to use one scenario card with the class before dividing them into pairs or groups to discuss their cards. You may also want to draw circles on the board to represent the biomass (organic) and atmosphere (inorganic) pools that students can use to illustrate the results discussion or ask questions.