Human Energy Systems | Activity 4.4

Target Student Performance

Students use an online computer model to make quantitative predictions of how changes in photosynthesis, cellular respiration, and combustion fluxes will affect the long-term trend in the atmospheric CO₂ pool.

Resources Provided

Global Computer Model
4.4 Global Computer Model PPT
4.4 Global Computer Model Reading (1 per student)
4.4 Global Computer Model Worksheet (1 per student)
4.4 Grading Global Computer Model Worksheet

Recurring Resources

Learning Tracking Tool for Human Energy Systems (1 per student)
Assessing the Learning Tracking Tool for Human Energy Systems
Questions, Connections, Questions Student Reading Strategy
(Optional) Big Idea Probe: What Would Happen if We Cut Fossil Fuel Use in Half (1 per student)
(Optional) Assessing the Big Idea Probe: What Would Happen if We Cut Fossil Fuel Use in Half

Setup

Prepare one copy of 4.4 Global Computer Model Reading and one copy of 4.4 Global Computer Model Worksheet for each student. Follow the link for the Global Computer Model short film to download it to your computer. Prepare a computer and projector for the film and 4.4 Global Computer Model PPT. You may want to prepare the poster papers around the room as described in step 4 of the directions.

Directions

1. Introduce the Activity.

Display Slide 2 of the 4.4 Global Computer Model PPT to show student where they are in the instructional sequence.

2. Revisit Carbon Pools and Fluxes.

Using Slide 3, revisit the three carbon pools in the global carbon cycle. Remind students that carbon can be found in the organic matter pool, inorganic pool and fossil fuel pool. Discuss what carbon might be found in in each pool.

Display Slide 4 and revisit the three carbon fluxes in the global carbon pool. Recall the processes that move CO₂ into and out of pools.

3. Revisit the long-term trend in the Keeling Curve.

Display Slide 5. Review conclusions made so far about global carbon cycling and about how the Tiny World Model can help explain the annual cycle of the long-term trend of the Keeling Curve.

4. Introduce Goals for Activity 4.4

Display Slide 6 of 4.4 Global Computer Model PPT. Revisit goals from past lessons and tell students that in this lesson they will aim to figure out how to accurately predict future CO2 concentrations

5. Introduce the Global Computer Model.

Display Slide 7 of 4.4 Global Computer Model PPT. Tell students that they will be using this online global computer model to help them answer their question of how they can predict future CO₂ concentrations.

Display Slide 8. Point out the various carbon Pools. Show Slide 9 to point out the various fluxes.

6. Reading About Global Pools and Fluxes

Have students take out 4.4 Global Computer Model Reading. Read through the reading, stopping at The Balance Between Photosynthesis and Cellular Respiration section on page 3. Use Slide 10 and/or the Questions, Connections, Questions Student Reading Strategy. See the Questions, Connections, Questions Reading Strategy Educator Resource document for information about how to engage students with this strategy.

7. Overview of how to use the Global Computer Model

Have students follow the URL to the Global Computer Model. The URL is on Slide 7 of 4.4 Global Computer Model PPT or on page 1 of 4.4 Global Computer Model Reading.

Display Slide 11 to show students how to change a size of a flux on the Global Computer Model.
Use Slide 12 to show students how to control when to the disturbance will begin and when the disturbance will end in the Global Computer Model.

Use Slide 13 to show students how to use the slider to choose a year to view in the results table. Refer to Slide 14 to show students how to read the table on the results page. Point out the year and what each number represents in the table so that they know what to record on their 4.4 Global Computer Model Worksheet.

8. Students Work to Complete Global Computer Model Worksheet

Students work alone or in pairs to complete Runs 1-4 on the Global Computer Model Worksheet using the online Global Computer Model.

9. (Optional) Have Students Compare Results and Discuss Patterns

Using Slides 15-17, have students compare their results and discuss patterns for their runs 1-3 on the 4.4 Global Computer Model Worksheet.

10. Students Read and Answer Remaining Questions

Have students read the final section in 4.4 Global Computer Model Reading, The Balance Between Photosynthesis and Cellular Respiration section, on page 3. Have students write answers to questions on the 4.4 Global Computer Model Worksheet either individually or in pairs.

11. Discuss answers to Run 4 and Questions about Patterns

Using Slide 18, have students discuss answers to Section B of the 4.4 Global Computer Model Worksheet.

12. (Optional) Revisit Earlier Predictions

Display Slide 19, have students revise and discuss their predictions for the Big Idea Probe: What Would Happen if We Cut Fossil Fuel Use in Half. Use the Assessing the Big Idea Probe: What Would Happen if We Cut Fossil Fuel Use in Half to aid in facilitating discussion of ideas

13. Have a discussion to complete the Learning Tracking Tool for this activity.

Show Slide 20 of the 4.4 Global Computer Model PPT.

Have students take out their Learning Tracking Tool from the previous lesson.
Have students write the activity name in the first column, "4.4 Global Computer Model."
Have a class discussion about what students figured out during the activity that will help them in answering the lesson driving questions:
What causes the annual cycle: CO₂ concentrations in Hawaii to go down every summer and up every winter?
What causes the long-term trend: CO₂ concentrations to go up every year?
How can we predict what will happen to CO₂ concentrations in the future?
When you come to consensus as a class, have students record the answer in the second column of the tool.
Have a class discussion about what students are wondering now that will help them move towards answering the unit driving question. Have students record the questions in the third column of the tool.
Have students keep their Learning Tracking Tool for future activities.
Example Learning Tracking Tool

Activity	What We Figured Out	What We are Asking Now
Activity 4.4: Global Computer Model	When the fluxes into and out of living and soil organic matter (photosynthesis and cellular respiration), then the unbalanced flux from fossil fuel combustion increases the size of the atmospheric CO₂ pool.	What else affects the size of the Earth’s atmospheric CO₂ pool?

Assessment

This activity includes opportunities for both formative and summative assessment.

Check for student understanding of the reading using the Questions, Connections, Questions Reading Strategy Educator Resource
Use 4.4 Grading Global Computer Model Worksheet to check for student understanding after the activity is over.
Check for changes in students’ predictions and strategies for predicting based on Assessing the Big Idea Probe: What Would Happen if We Cut Fossil Fuel Use in Half
Compare your students’ summaries of what they learned and questions to the suggestions on Assessing the Learning Tracking Tool for Human Energy Systems

Tips

You might want to point in step 5 out that although the seasonal cycle is a naturally occurring phenomenon, the current overall trend in increases in CO₂ and temperature cannot be explained using evidence of natural cycles. Students may point to specific natural cycles as evidence that climate change is not caused by humans, which might include sunspots, volcanic activity, El Niño, or changes in the Earth’s rotation around the Sun. While it is true that these natural phenomena do cause variations in shorter time periods (1-15 years or so), these variations do not contradict the evidence for the recent increase in CO₂ levels and temperature, especially in the last 60 years. These increases have persisted over a longer time period than natural causes like sunspots and volcanoes can explain.
It won’t hurt to mention a few times that the fossil fuel pool has nothing to do with the seasonal flux!