Geoboard

Choose a mode

Tap pegs to place the corners of your shape — the band connects them and closes the loop. Tap the last corner again to undo it. Build any shape whose area matches the target, then press Check.

3D math game · Best for grades 3-5

Geoboard

Geoboard lets students stretch a virtual rubber band over a peg grid to build any shape they like, as long as its area hits the target number of square units. There is no single correct shape — only shapes with the right area — so the game rewards spatial exploration over formula recall.

What students practice

Counting square units inside irregular polygons on a grid develops area intuition that later supports the formula approach. Students discover that many different shapes can share the same area — a spatial insight that the rectangle-formula alone cannot give.

  1. Read the target area shown above the board.
  2. Tap pegs to place the corners of your polygon; the band stretches between them and closes into a shape.
  3. Watch the live area counter as the shape grows; adjust corners by tapping a peg again to undo.
  4. Press Check when the enclosed area equals the target.

How to use it at home or in class

For area 6 a student might build a 2×3 rectangle, an L-shape, or a triangle with base 4 and height 3. Each works, and comparing them on screen shows that area is a property of the enclosed region, not the shape's outline.

Students frequently trace the perimeter of the grid squares (counting edges) instead of the enclosed squares (counting area). The game counts enclosed square units precisely, so border-tracing strategies show the wrong answer and prompt recounting.

Use it for individual practice, paired work, or a short class demonstration before worksheets.

Start with the game above, then continue with written practice to reinforce the skill.

Common questions

Does the shape have to be a rectangle?
No. Any closed polygon whose corners sit on pegs is valid, including triangles, L-shapes, and irregular quadrilaterals — as long as the enclosed area matches the target.
Which grades is this game for?
It fits grades 3-5, from first encounters with area as square-unit counting through more complex polygon shapes.
How is this different from Volume Builder, which also counts unit cells?
Geoboard works in two dimensions — area in square units on a flat grid. Volume Builder works in three dimensions, counting cubic units to fill a box. Same counting logic, different geometric dimension.