A game with a secret, and the secret is arithmetic
Nim
Take counters from rows, and whoever takes the last one wins. It looks like luck until a child finds the pattern, and finding the pattern is the point.
- Players
- 2
- Time
- 2 minutes a game
- Ages
- 7 and up
What you need
- Counters, coins, pasta or matchsticks — about twelve
How to play
- Lay out the rows. Make three rows with 3, 4 and 5 counters. Any counters will do.
- Take from one row. On your turn take as many counters as you like — but they must all come from the same row, and you must take at least one.
- Win by taking the last. The player who takes the very last counter wins.
- Play it many times. Play again and again. Somewhere around the tenth game one player starts winning nearly always, and that is when the real conversation begins.
The maths in it
Nim has a complete mathematical solution, and children discover fragments of it unaided — first 'leave two equal rows', then more. It is one of very few games where a child can find a genuine theorem by playing, and the experience of a pattern turning out to be a rule is worth more than the rule.
Making it fit the child
Easier: Start with a single row of counters and a rule that you may take one, two or three. The winning pattern there is multiples of four, and most children find it within a dozen games.
Harder: Play misère Nim, where the player who takes the last counter LOSES. The strategy changes near the end in a way that surprises adults.