Nontransitive Dice

Nontransitive Dice are pretty amazing things. Basically, in these dice, when they are set up pairwise, one die will beat another 2/3 of the time. However, there’s no “best” die. Even though A beats B and B beats C, A DOES NOT BEAT C. I bought a wonderful pair of Efron’s Dice from the Museum of Math.  For the math nerd, you really have to get a set. They’re amazingly interesting and they really teach kids about probability in a wonderful way!

Without going into all the details, normally, when you play dice you assume transitivity:

  • If B beats A
  • And if C beats B
  • Then C beats A

Which sounds obvious; however, it’s not. take, for example, the game rock, paper, scissors.

Rock-Paper-Scissors from Wikipedia

In this case:

  • Rock beats scissors
  • Scissors beats paper
  • But rock DOES NOT BEAT paper.

How to Painlessly Get Your Kids To Memorize Facts

Math Books

Hard Elementary School Math is a great book covering a wide variety of topics that are appropriate for elementary school. A Mathematician’s Lament (free abridged version here) is a great book on math education — focusing on how kids should be learning math. For those of you that want a more “adult” basic math book, check out , Steve Strotgatz’s Joy of X is quite good — you can also read a number of his articles in the New York Times. Bedtime Math is also fun — we like it but it’s especially for parents who aren’t so into math.