When my son was three, he was one of fifteen kids in a nursery school class. The teachers played one game that the kids liked a lot. They would have all the children close their eyes. Then they would quietly take one child out of the classroom. Then the others opened their eyes, and the teachers challenged the children to figure out who was missing.
If you think about it, I'm sure you will see all sorts of benefits to making three year olds play this game. I have always remembered it, because I think the game would have been a good challenge for me, too.
This morning, after a BIG eating weekend, I weighed 219.6.