Activity Icon - Don't Say 13.png

Don’t Say 13

How it works

Don’t Say 13 is a two player game where students take turns counting numbers starting from “one”. Each turn, a player can say one or two consecutive numbers continuing from the last number the other player said. So, for example, Player 1 might say, “One, two,” and then Player 2 might say, “Three, four,” and then Player 1 might say, “Five,” and so on. Whichever player says “thirteen” loses the game.

After playing the game and discussing strategy with their table, students explore what happens if instead the player who says “thirteen” wins the game instead of losing. They then look into strategy for changing which number is their target for winning the game.

Say 13 Handout
Say "Blank" Handout
Skip 3 Bracelets

Why we like this activity:

  • It’s fun! Students enjoy playing and mastering the games and making the bracelets.

  • It helps to develop game-theoretic reasoning.

  • It helps to develop intuition about important relationships between numbers.

  • It requires students to engage in mathematical habits of mind:

    • Finding and using strategies to win at the different games no matter what your opponent does.

    • Looking for patterns / finding similarities and differences / making and testing predictions when exploring the strategies for the different games.

  • It has a low floor and high ceiling: Students can get started solving playing Don’t Say 13 by trial and error, but they can discover a more effective strategy, and then they can adapt and generalize this strategy to the variations of the game.

To find out more about our approach to math and math education, click here.