I'll gather up a bunch of pennies, buttons, safety pins and small pieces of uncooked pasta and mix them together. Then, I'll have the kids sit near each other and then divide the mixture between them. On the "go" signal, the kids will start sorting the objects into piles: a pile of pennies, a pile of buttons, etc.
Whoever sorts all of their objects into piles first is the winner, and the winner gets to decide where everyone sits at the table for lunch.
This game can also be played by one child. He can either compete against himself by timing himself on an egg timer and then trying to beat his previous time, or he can play without a time limit and simply sort the objects for fun.