Density

How do students use and coordinate their understanding of weight and volume in an emerging understanding of density as a property of materials?

We developed three tasks to probe children’s developing understanding of density. None of the tasks relies on formulas or technical vocabulary. The tasks were designed to determine:

• How children explained the fact that some smaller objects are heavier than larger ones.
• Whether children could consistently distinguish between the weight of an object and the heaviness of the material from which it was made.
• Whether they could infer whether two objects were possibly made of the same material, based on their size and weight.

At the start of grade 3, children were inclined to confuse weight and density on these tasks. (This is consistent with our past research.) However, by the end of 4th grade, almost three-quarters of the Inquiry students showed some insight on at least one of the three tasks, compared to less than half of the Controls.