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Ecosystems | Activity 3.3

Activity 3.3: Tracing Carbon Through an Ecosystem (30 min)

In this activity students shift to following a pulse of 500 carbon atoms through all the carbon pools in an ecosystem, considering the carbon transforming processes (eating, digestion, biosynthesis, photosynthesis, cellular respiration and death/defecation) that move atoms from one pool to another. They see how the pattern they observed in Lesson 2—the organic matter pyramid—emerges from these carbon-transforming processes.

Materials You Provide

  • Computer
  • Projector

Resources Provided


Print a copy for each student of 3.3 Tracing Carbon Worksheet. Set up a computer and projector for 3.3 Tracing Energy PPT.


1. Revisit student ideas about the Carbon Fluxes Question.

Use 3.3 Tracing Carbon PPT, Slides 2 and 3 to discuss the patterns students found in Lesson 3.1 The Carbon Dice Game. Remind them that in the game they followed individual carbon atoms. Now, they will be tracing multiple carbon atoms through an ecosystem.


The description of student answers on 3.3 Assessing the Tracing Carbon Worksheet will give you an idea of how your students are conceptualizing the movement of carbon through an ecosystem. Use this as a formative assessment: if your students are having trouble describing carbon atoms moving through pools, you may want to go over the answers to the worksheet as a class and may need to review these processes.


For this activity you will need to revisit some materials from Activity 3.2 Carbon Dice Game.


Before showing Slide 5 of the presentation, have students explain some of their initial ideas with the class as well as with their partner.

Extending the Learning

Challenge the students to think about what would happen to a plant or animal in this ecosystem if they could not perform cellular respiration.