A device commonly used in elementary schools to aid in the teaching of basic
geometric concepts. A simple geoboard can be made from a square piece of
wood and 25 nails arranged in an evenly-spaced grid of 5 vertical lines
and 5 horizontal lines. These nails represent the lattice
points in the plane. Figures are made on the geoboard by stretching
rubber bands from one nail to another until the desired shape is formed.