Worksheets and lesson ideas to challenge students aged 11 to 16 to think hard about density (GCSE and Key Stage 3)
Still to this day I struggle to explain why a ferry floats but a penny sinks! I think for children floating and sinking pose similar challenges. Is a needle on the surface of water floating? Or it is just being help up by surface tension? Do submarines float when they are not on the surface of the water but maintaining a constant depth? Does the depth of water in a beaker affect the level of a floating object? Explaining floating and sinking in terms of density offers a clear explanatory framework that I think helps children to understand.
Key Stage 3 practical activity on calculating density. Students use the particle model to help understand what density really means. Using an idea adapted from Candy Experiments, solutions of different concentrations and colour are layered on top of each other to create a rainbow. Students draw particle pictures for each layer and then calculate the density. (PDF)