Of all the neat experiments we've done this year, this is one of the most successful and clear. The exercise is about how friction can stop things from rolling. The idea is that if a can, like a can of soup, is full to the top, it will roll easily down a hill. However, if it's only partly full, the friction of the contents inside against the side of the can will stop it from rolling far or fast.
Olivia rolled the cans to Gabe just a few feet away down a shallow slope in the driveway.
The can rolled easily. She didn't even have to push it.
However, when we tried it with a 1/3-full container of oats, the friction inside the container wouldn't let it roll at all.
Even pushing it only got it to go about 3 inches.
Ezra wound up pushing it the whole way to Gabe.
To further illustrate just how strong that force can be, I tried kicking the can down the steep part of our driveway. It went about a foot before it stopped. It was quite impressive, really.