Density

Children (and adults) often experience difficulty understanding the relationship between mass and volume. "Density" is the expression defining that relationship. The purpose of this lecture is to help children understand both density and buoyancy.

By the end of the lecture children will understand why a tiny pebble sinks whereas a tree trunk, thousands of times heavier than the pebble, still floats. The explanation centres around determination of the density of some of the children themselves. Finding the weight of the child is easily understood and it doesn't take long before they appreciate what we mean by volume, since it is the children who collect the buckets of displaced water as one of them is placed into a barrel of water!

Time allowing we can also conduct a workshop or a demonstration of how submarines can alter their density to control floating and sinking. This is demonstrated by creation of a working submarine in a plastic bottle.