Formative Assessment

How do your students explain the process of condensation?

Listen to their discussion of condensation inside the 2–bottle system to find evidence that students understand that water vapor is the source of water droplets formed during condensation.

Use these criteria to interpret students’ explanations. Do students explain that:

• Water vapor in the upper bottle is the source of the water droplets on the inside surface of the bottle?
• Condensation is the transformation of water vapor (invisible) to visible drops of liquid water on the inside of the bottle?
• Condensation occurs when water vapor comes in contact with a cool surface?

Make sure that everyone in the class understands the transformation of water vapor to water. The next step is to link this process to the process of evaporation.