Free local tool

Virtual Geoboard

Construct shapes on a bounded peg grid with pointer, touch, or keyboard controls and a textual peg sequence.

Private by design: inputs stay in this browser tab. The tool sends no input to a server and stores nothing after the page closes.

Select pegs with a pointer, touch, or keyboard. Each selection extends the current band.

Constructed shape

JavaScript is required for the interactive tool.

Method and limits

Uses an integer peg-coordinate model on 3×3 through 15×15 rectangular boards. The current shape is limited to 100 vertices and remains in memory only. Closed simple polygons show shoelace area and Euclidean perimeter; self-intersecting polygons are detected and do not receive an ordinary area. This is a classroom manipulative, not a coordinate graphing page.