Aurora Lipper has posted on her blog a neat science activity. It's a can that rolls back to you... she says most adults can't explain why it works.
We made it just this morning, just with a bigger can than what Aurora used, so it rolled a longer way before turning back.
I like this activity because
1) it's so simple and quick to make,
2) kids loved it
3) it works
4) it illustrates a very important principle in science.
Go take a look!