This all reminds me of my 7th grade science class: we went outside (on a beautiful spring day) on the football field and had big blue trays of sand and that we could set at different angles. There was a hose at the top of the trays that let us also control the flow of water.
From there we were able to create mini 'rivers' and watch how the courses changed, forming ox-bow rivers etc. I remember realizing that what had happened at False river, where friends had a camp that we'd go skiing and hang out.
It was a great lesson and one that has stuck with me all these years.