Look for: Which sample is less dense?

5.A.2 Conduct investigations to collect and use observations and data as evidence to determine the effects of thermal energy transfer to the air in contact with Earth’s surface.

After the second scenario, list for these ideas again:

Which sample is less dense?

• Sample A has a greater number of molecules in the same amount of space as Sample B.
• Sample B is less dense than Sample A because it has fewer molecules that are less densely packed in the same size space.

What caused this difference?

• The ground in direct sunlight receives more sunlight than the ground in the shade.
• The blacktop absorbs more sunlight and gets warmer.
• The air is heated through direct contact with the ground (conduction).
• The air over the blacktop gets warmer than ___, because the blacktop has more thermal energy than ___.
• The molecules that make up the air over the blacktop have more energy, move faster, and spread farther apart, so the air in Sample A is less dense than the air in Sample B.

Students may still need additional scaffolding to talk about density. Continue to use prompts, such as Sample ___ is less dense because ___________. When a sample of the same type of matter is less dense than another sample of that matter, the particles that make it up _________________.