The density of a substance is an essential feature to identify a substance at specified temperature and pressure conditions . With the help of the " density " substances can be characterized and divided in different classes ( metals in heavy and light metals ) . In this experiment students learn about the physical quantity " density ", defined as mass : volume ( g / ml) . Students recognize in this experiment , that with irregularly shaped bodies , the density can be easily determined, the mass by weighing and the volume by water displacement ( Archimedes Pinciple of water displacement ) . The density of different solids is also determined in this experiment, using the example of lead, iron , copper, brass , zinc, aluminum , hard rubber and wood.