Nim - A 1000 Year Old Math Game

I briefly taught a new math game today - we will partner up and play tomorrow. It is called Nim, and it is a very old game indeed. Variations have been played since ancient times. I told the children that it is at least 1000 years old. Can you imagine?

This game is said to have come from China, which is why it interested me now (although I teach it every year). It closely resembles the chinese game of Jianshizi or "picking stones". I taught it today using actual stones, and my math group talked why it probably was first played this way. The students thought that plastic discs were probably not available 1000 years ago!

You can play at home. It is fun and easy (although difficult to play well). Here are the rules I plucked from the Scholastic website (we will play with 21 small things tomorrow):

1. Instruct your child to find 15 small things, for example: buttons.
2. On each player's turn, he or she can take one or two buttons away. Take turns doing this.
3. The loser is the player who takes the last button.
4. Eventually, you can teach your child the winning strategy: Just make sure on her turn she leaves 13,10, 7, 4 or 1 objects. (Susan's note: please don't do this right away as I want to see if anyone can come up with the strategy by themselves!)
5. Give the game a challenging twist by using a different number of objects or by taking away different amounts.