Directions 1. Use the instructional model to show students where they are in the course of the unit. Show Slide 2 of the 4.2 Carbon Pools and Constant Flux Simulation PPT. 2. Review the patterns found in Activity 4.1. Show Slide 3 of the 4.2 Carbon Pools and Constant Flux Simulation PPT. Have students discuss the patterns they found in Activity 4.1 and review the idea of net flux. 3. Introduce the Constant Flux Simulation. Show Slide 4 of the 4.2 Carbon Pools and Constant Flux Simulation PPT. Pass out a 4.2 Computer Model for Constant Flux Worksheet to each student. Have students read until #1 for an overview of the simulation. Show Slide 5 and open the simulation. Show students how to move the sliders and run an example. Point out the graphs and how they can slide the line of the graph to get data for a particular point in time. 4. Students run the simulation. Display slide 6. Have students follow the instructions to run the simulation. Students should record their data in the table on their worksheet. (Optional) Use slide 7 and 8 to discuss Run 1 and Run 2 as a class. 5. Students consider patterns in their results. When students have completed the table, have students work individually and then with a partner to answer questions 6 and 7 on 4.2 Computer Model for Constant Flux Worksheet. (Optional) Use slide 8 to complete the table as a class. 6. Discuss the patterns. Show Slide 10 of 4.2 Carbon Pools and Constant Flux Simulation PPT. Have students share and discuss their answers to questions 6 and 7. 7. Review the patterns. Show slide 11. Discuss with students how the rules from Activity 4.1 in the tiny system also are true of the larger system in the simulation.