The Geoboard tool opens with 1 shape on the board. The shape behaves like an elastic band - you can click and drag any point of the shape’s perimeter to change the shape. You can add up to 2 more shapes to the board, by clicking the Show Shape buttons at the bottom of the screen. To delete a shape, click its Show Shape button again.

Clicking Reset undoes all changes you have made, returning the tool to its default state.