An experimental approach to the concept of density

A teaching project dealing with an experimental introduction to the concept of density, planned for science courses at the lower secondary school level, is described. A group of teachers was introduced with the project during a training course; in the following year they adopted it in their classes (6th, 7th, 8th grades), for a total of 389 pupils.

The approach followed in the project is based on presenting the pupils with a range of solid objects (rods, balls, blocks) made in different sizes and materials. These are weighed and their volumes measured by dipping them into a graduated vessel and reading the rise of water level. Graphs of mass versus volume for objects of the same material are found to be linear, with the slope of each plot being a characteristic of a particular material, viz. its density.