A geoboard is a board with regularly spaced pegs. It is used for exploring plane figures. A typical geoboard has a square shape with pegs spaced 1 unit apart.
A geoboard is often used with rubber bands (geobands) for constructing plane figures. Many planar figures and geometric concepts can be constructed using a geoboard and geoband. The following are some of them.
Perimeter and area
The perimeter of the quadrilateral above is .
Count the unit squares inside of the quadrilateral to determine its area. There are 22 unit squares and 4 half squares along the diagonal side so the area is 22 + 4 × 0.5 = 24.
The red and blue pentagons above are similar figures.