A Lesson in Gravity

A few weeks ago the children started making streams and river and inlets and lakes and and and and..... It was pretty apparent that the children discovered a new interest.
In our sand pit we have a rain barrel ready and waiting for the children to explore and play with water.
A few months ago I placed some rain gutters in the sandpit, and the children used them here and there, but didn't really take to them. In fact, when they initially used the gutters the children tried pouring the water into the low end, and the effect was lost on the children as the water immediately ran out 'backwards'.
So it was when I brought out the hammer and the nail, and a few pieces of wood, that the children's interest peaked. They came to take a closure look and soon the children started putting together a sluice way, and quickly became invested in creating a gravity fed stream/waterfall.

It took a while to perfect it, and a couple children remembered what we discovered in the last few times of creating streams. It was pretty obvious that the problem of gravity was solved.