Formative Assessment

What happens to weight when water freezes?

You can find evidence of students’ ability to interpret class data by listening to their make meaning discussion.

Listen for these ideas about discrepant weight data as you interpret students’ explanations:

• A small weight increase occurred because we didn’t wipe off the condensation that was added to the outside of the container.
• A weight loss is due to water seeping out of a cracked container.
• A small change in weight (+/- 1-2 grams) could be due to the inaccuracy of the scale.

A next step might be to have students return to their predictions and ask if anyone is thinking differently now about what happens to the weight and volume of water when it freezes.