Human Energy Systems | Activity 4.2

Display Slide 3. Tell students that this unit is different from other Carbon TIME units because of the scale. Instead of looking at how carbon and energy move through an animal or a plant or a decomposer or an ecosystem, we are looking at how carbon and energy move around the entire world (i.e., at a large scale). By world, we mean the Earth and atmosphere for matter, and the sun and space for energy.

Use Slide 4 of 4.2 Carbon Pools and Fossil Fuels PPT to introduce the main image for this unit.

• Tell students that we will use this picture to talk about how carbon and energy move through our world. This picture represents just a small portion of the larger Earth systems we are examining in this unit.
• Ask students for initial observations about what this picture has in it and where they see different Earth systems represented.
• Display Slide 5. Use the animation to make connections between the image and the more abstract “box diagrams” we use to represent the carbon pools.
• You may want to point out two interesting things about these pools:
• The biomass pool contains carbon found in the form of living things (including people) and recently living plants and animals. Most biomass on the earth is stored in the wood of trees and other plants.
• The soil organic carbon pool is a large pool of carbon (as large as the atmosphere and biomass pools combined). It contains carbon in the form of dead organisms (plants, animals, and decomposers) and living decomposers.

Use Slide 6 to introduce students to the language you will use to discuss pools of carbon at a global scale: Plants, animals, and soil organic carbon pool), atmosphere (inorganic carbon pool), and fossil fuels (organic carbon pool).

• Note that the ocean pool is intentionally omitted here, even though the ocean stores a lot of carbon.

Display Slide 7 and tell students that the will spend the rest of the activity talking about one particular carbon pool: the fossil fuels pool. Ask students: “What are fossil fuels?” and “Where do they come from?” and “How do we use them?”

After you hear their initial ideas, use Slide 8 to ask students to share any ideas about the three fossil fuels they see in the slide: coal, oil, and natural gas.

Use Slides 9-13 to “zoom” into fossil fuels at a molecular scale.

Using the slides, lead the students through a discussion in which they compare the molecules of gasoline/octane to other molecules to decide if gasoline/octane is organic or inorganic. Remind students that in Carbon TIME units, organic molecules 1) are carbon based, and 2) contain C-C and C-H bonds.

Display Slide 14. Tell students that fossil fuels contain chemical energy that is very useful to humans.

Show Slide 15. Give each student a copy of 4.2 Carbon Pools and Fossil Fuels Reading and a copy of the Four Questions Handout (or have them take out their existing copies). Have students read 4.2 Carbon Pools and Fossil Fuels Reading using 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. Put a copy of the Four Questions 11 x 17 Poster on the wall for reference if it is not there already.

Use Slides 16-18 to briefly overview how fossil fuels form. Key information to point to during this presentation is that fossil fuels were formed from dead plants and animals that were exposed to heat and pressure over time. This is why fossil fuels contain energy-rich C-C and C-H bonds, and this is also the reason that we label fossil fuels pool an “organic” pool.

Display Slide 19 to aid in discussion about “Where does chemical energy in fossil fuels come from?” Remind them of the Four Questions.

Display Slide 20. Tell students they are going to focus on the carbon cycling question and the energy flow question as it pertains fossil fuels.

Use Slides 21-23 to discuss how fossil fuels are formed, extracted and combusted.

Use Slides 24-25 to show how the carbon cycles and the energy flows in this same system.

Display Slide 26. Use the figure to discuss the role of fossil fuels in the overall carbon cycle.

Use Slide 27 to further discuss carbon cycling and energy flows.

Display Slide 28. Tell students they are going to focus on the stability and change question.

Display Slide 29 to start a discussion about how humans started using fossil fuels.

Slide 30 continues the conversation about how human still use fossil fuels today.

Show Slide 31. Tell students they will now watch a time-lapse video showcasing how CO₂ emissions have changed overtime. Have students share patterns they noticed as well as overall impressions.

Display Slide 32 to discuss the stability and change question.

Show Slide 33 of the 4.2 Carbon Pools and Fossil Fuels PPT.

• Have students take out their Learning Tracking Tool for Human Energy Systems.
• Have students write the activity name in the first column, "Carbon Pools and Fossil Fuels."
• 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

• Show Slide 35 of the 4.2 Carbon Pools and Fossil Fuels PPT.
• Conclusions: What are fossil fuels and how did they form?
• Predictions: How does burning fossil fuels affect CO₂ concentrations?
• On a sheet of paper or a sticky note, have students individually answer the exit ticket questions. Depending on time, you may have students answer both questions, assign students to answer a particular question, or let students choose one question to answer. Collect and review the answers.
• The conclusions question will provide you with information about what your students are taking away from the activity. Student answers to the conclusions question can be used on the Driving Questions Board (if you are using one). The predictions question allows students to begin thinking about the next activity and allows you to assess their current ideas as you prepare for the next activity. Student answers to the predictions question can be used as a lead into the next activity.