Because density is unobservable and must be inferred from knowledge about weight and size, it is a difficult concept to teach and learn. Even after traditional instruction, many students still have an undifferentiated concept that mixes characteristics of both weight and density. In this study, researchers tested the effectiveness of a unit they…

Density is the first intensive physical quantity students encounter that can be understood in terms of an underlying model, the particulate theory of matter. Learning about density provides students with explanations for a range of phenomena such as sinking and floating, and changes of state. Teachers report, however, that density is a difficult…