About this game

The computer buries a chest somewhere on a gridded island. The left and right sides of the room take turns calling a spot, and you tap it or type it in. A shovel digs there. If the chest isn't there, the hole gets a badge with the number of steps to the chest, counted across and up or down.

Each side's digs are listed under its name, so the class can use the clues so far to work out where to dig next. The side that finds the chest scores it, and the next round starts with the other side.

How it works

1. Pick a grid. Start with lettered squares like C4, move on to (x, y) points, then all four quadrants with negative numbers.
2. Choose the clue: the number of steps, or a word from Boiling to Cold for younger classes.
3. Tap a spot to show its name, then tap again to dig. Undo takes back a wrong tap.
4. Stuck? Show chest reveals where it was buried.

Good for

• Practising reading and plotting coordinates, x before y
• Introducing negative coordinates
• Counting distances on a grid
• A ten-minute warm-up or end-of-lesson game