Basically you make a mountain of sand representing soft rock. Bury something hard in the mountain to represent hard rock - we used a brick. Pour water (rain) on top of the mountain and watch the river form. The water wears away the sand quickly. The hard rock does not wear away. Eventually the soft rock downstream wears away and a step or waterfall is formed where the two rock types meet.
You can see a good animations showing the process here and here.
Afterwards R read through some reference books on rivers and drew this diagram.
|A river by R|
Today L wanted to know why convicts get put in prison. She has been very interested in convicts since we went to Dubbo Gaol (scroll down on this link for that part). We looked for books in the library but they are all way too complicated for a 4 year old. However we stumbled across this website from the Hyde Park Barracks. There's lots of pictures, videos and activity ideas here. We haven't visited the barracks yet so we will do that soon.