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For teachers
Number Islands in the classroom
A free, ready-to-print activity for logical reasoning. Here's how teachers and parents can run a 30-minute session.
Our printables are free for personal and classroom use. Each one is a single black-and-white page with the rules, a puzzle, a progress tracker, a tip and an upside-down answer. They work well as a warm-up, a learning-centre activity or a quiet-time challenge.
What students practise
- Deductive reasoning. Every move has a reason that can be said out loud: “these two squares can't be on the same island, because both have a 3.”
- Spatial thinking. Students picture regions, count squares and test whether a shape can still grow to six.
- Persistence and checking. The puzzle tells you when something is wrong, because a row ends up with two of the same number or an island has seven squares.
- Mathematical talk. Words like row, column, region, adjacent and constraint come up naturally.
A 30-minute session
- 5 minutes: the rules. Project the interactive guide and walk through the four tiny lessons together.
- 15 minutes: solve in pairs. Hand out Printable No. 01 or No. 02. Pairs take turns: one proposes a move, the other must agree with the reason before it goes in pencil.
- 5 minutes: share a move. Ask a few pairs to explain their favourite deduction. Collect the reasons on the board. They'll match the six moves in our strategy article.
- 5 minutes: check and reflect. Students fold the page to reveal the solution. Discuss: where did you get stuck, and what helped?
Choosing the right level
| Group | Printables | Notes |
|---|---|---|
| First-timers, younger solvers | No. 01–07 (The Shallows) | Lots of clues; most moves are sealed sixes and last numbers. |
| Confident solvers | No. 08–13 (Coral Reach) | More counting; numbers start drawing coastlines. |
| Puzzle club, extension | No. 14–19 (Ember Cliffs) | Fewer clues; trapped pockets appear. |
| Challenge table | No. 20–25 (The Far Storms) | The hardest set. Expect to erase. |
Tips from the lighthouse
- Use pencil for coastlines, and ink them only when sure.
- Shade each finished island lightly. Seeing the map fill in is very motivating.
- Stuck? Count the squares in each open area. If one can't be split into sixes, a coastline must be wrong.
- Each page fits US Letter and A4. Choose “Fit to page” if your printer asks.
Number Islands collects no data, and the app has no ads or accounts, so it's comfortable to recommend to families too.
