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

Use Slide 3 to discuss the initial patterns students found in the Carbon Dice Game.

Use Slide 4 to introduce the purpose of this activity: using the results of the Carbon Dice Game to answer the Carbon Cycling Question.

Show Slide 5 of the 3.3 Tracing Carbon Through Ecosystems PPT. Explain that the diagram shows an overall picture of carbon cycling and energy flow in ecosystems.

• Use Slide 6 to discuss the left side of the diagram, showing how carbon cycles from inorganic to organic carbon pools.

Use Slide 7 to discuss the right side of the diagram, showing carbon pools as rectangles and carbon movement as arrows. The green rectangles are organic carbon and the grey rectangles are inorganic carbon. For this Activity, students will be using the right side of the diagram.

Pass out copies of the 3.3 Tracing Carbon Through Ecosystems Graphic Organizer.

• Have students complete the graphic organizer by writing the process represented by each arrow on the line in each arrow.
• When students are finished, show Slide 8 to allow students to check their graphic organizers. Talk with students about which arrows are carbon transforming processes (photosynthesis, cellular respiration) and which arrows are carbon moving processes (falling leaves, death, eating).

Have students take out their 3.2 Carbon Dice Game Tracking Sheet. Display slide 6.

Have students use a pencil to trace how they traveled during the carbon dice game on their graphic organizer. Each time they reach the bottom of the diagram they should circle back to the top (the top and bottom pool are the same).

Show Slide 10. Ask students to find the organic matter pyramid on their graphic organizer, then show where it is located.

The 3.3 Supplement PPT includes animation that has a different representation of the organic matter pyramid, following 500 carbon atoms through a meadow ecosystem and showing the numbers of carbon atoms that reach different carbon pools.

Display Slide 11. Have a discussion about carbon cycling to explain the small amount of organic carbon that reaches carnivores.

Show Slide 12 to recap some of the main points about the processes that cause carbon to cycle in an ecosystem.