Primary 4 have been exploring materials over the last few weeks. After testing the solubility of various substances we investigated the effect heat has on the solubility of salt. Today we discussed the meaning of volume and density. Pupils made predictions based on their knowledge of five common liquids ordering them in what they thought would be heaviest to lightest. Some pupils predicted they would all weigh the same. We weighed each one and recorded the results. After this we proved the density by layering the five liquids to create a 'Density Rainbow'. Lots of fun, great discussion and learning.