Geoboard
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.
![](/img/a/geometry/shapes/geoboard/geoboard.png)
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.
Line segments
![](/img/a/geometry/shapes/geoboard/geoboard-line-segments.png)
Angles
![](/img/a/geometry/shapes/geoboard/geoboard-angles.png)
Perimeter and area
![](/img/a/geometry/shapes/geoboard/geoboard-perimeter.png)
The perimeter of the quadrilateral above is .
![](/img/a/geometry/shapes/geoboard/geoboard-area.png)
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.
Similar figures
![](/img/a/geometry/shapes/geoboard/geoboard-similar-figures.png)
The red and blue pentagons above are similar figures.