Look for: The ground warms the air near it through cond…

5.B Develop and use a model to track and describe how transferring thermal energy to and from a fixed amount of air (matter) in a closed system affects its volume and density due to unobservable mechanisms (causes), including changes in the speed and spacing of the molecules that make up that air.

• The ground warms the air near it through conduction.
• As the air near the ground warms, the molecules that make up the air speed up and spread farther apart.
• The warm air becomes less dense than the cooler air above it.
• The warm, less dense air rises.
• As the warm, less dense air rises high up in the atmosphere, it transfers thermal energy to the cooler air around it.
• The warm, less dense air cools down, becomes more dense, and sinks back down toward the ground.

If students struggle to model what happens to the air near the ground when it is warmed up, have them think about the important components--air, the ground, and energy--and the interactions between them. Encourage them to use words and pictures to represent how energy affects the ground and the air near it. You can also prompt them to think about the changes in energy caused in the air in the Soap Bubble and Bottle Investigation and in the helium in the Heated Balloon Investigation. You can also revisit the lesson question at the beginning of the next class by analyzing one or two examples of completed Progress Trackers with students.