Islands and Bridges
How it works
Imagine that you have a group of islands, each of which has a number associated with it, as in the picture above. Your goal is to build bridges between these islands. The bridges have to follow the five rules below:
Bridges can only be vertical or horizontal (not diagonal).
Bridges can't cross each other.
There can't be more than 2 bridges between a pair of islands.
The number of bridges connected to an island must match the number for that island.
It must be possible to get from any island to any other island using the bridges.
In this activity, students explore a variety of different bridge-building puzzles with different sets of islands. Some of these puzzles are possible, and some are impossible! As the puzzles get more complex, students have to think more carefully and strategically about how to build bridges that follow all the rules.
Why we like this activity
- It’s fun! Students enjoy making bridges and solving the puzzles.
- It helps students develop numerical reasoning.
- It requires students to engage in mathematical habits of mind:
Using logic and finding and using strategies to figure out where to build bridges to solve the puzzles
Using logic to decide when a puzzle is impossible
- It has a low floor and a high ceiling: Students can get started solving puzzles by trial and error, but more complex puzzles require more careful strategizing.
This activity was inspired by one of the many excellent puzzles on BrainBashers.