Tic-Tac-No
How it works
Tic-Tac-No is similar to Tic-Tac-Toe, but there are some important differences. Here's how to play:
- In Tic-Tac-No, there are only Xs, no Os.
- Two players take turns placing Xs.
- In Tic-Tac-No, if you place an X so there are 3 Xs in a line (horizontal, vertical, or diagonal), you lose.
- You lose if you make 3 in a line using any 3 Xs, not necessarily just the Xs you've placed.
So your goal is to avoid making 3 in a line, and to force your opponent to make 3 in a line.
In this activity, students start by playing the game on a 3 x 3 board against each other. When they're familiar with the game and have started to develop some intuition and basic strategies, they switch to playing against an expert.
When they're able to figure out how to defeat the expert, they play a solitaire / cooperative version of Tic-Tac-No where the goal is to place as many Xs as possible on the board, and they explore playing Tic-Tac-No on a bigger board.
Why we like this activity
- It’s fun! Students enjoy playing the game and trying to figure out how to beat an expert.
- It helps students develop algorithmic reasoning.
- It helps students develop numerical reasoning.
It requires students to engage in mathematical habits of mind:
Finding and using strategies to beat an expert.
Finding and using strategies to place as many Xs as possible on the board without making 3 in a line.
Understanding and explaining why you can't place more than a certain number of Xs on a board without 3 in a line.
- It has a low floor and a high ceiling: It's easy for students to start playing Tic-Tac-No by trial and error, but figuring out how to beat an expert is more challenging!