Blockade
How it works
Blockade is a 2-player game. Here's how to play:
- There are 2 circles.
- The players take turns placing numbers in the circles.
- First, Player 1 places 1 inside one of the circles, then Player 2 places 2 inside a circle, then Player 1 places 3, etc.
- You can't place a number inside a circle if there are 2 numbers already in that circle that add up to the number you're trying to place. (For example, if 1 and 2 are in the same circle, you can't place 3 in that circle, because 1 + 2 = 3.)
- You win if your opponent can't make a move (that is, if the next number they have to place is blocked in both circles).
Can you beat an expert at this game?
In this activity, students start by playing the game against each other. Next, they play against an instructor who is an expert at the game (that is, the instructor always makes the best possible move). Students' goal is ultimately to be able to beat the expert.
When students have figured out how to beat an expert, they explore other versions of the game (for example, playing with only the odd numbers, or only the even numbers, or starting at 2, etc.)
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 and game-theoretic reasoning.
It requires students to engage in mathematical habits of mind:
- Finding and using strategies to beat an expert.
- Comparing and contrasting strategies for different versions of the game.
- It has a low floor and a high ceiling: It's easy for students to start playing the game by trial and error, but beating an expert is more challenging!
This activity was developed in collaboration with the Julia Robinson Mathematics Festival.