Large Geoboard - Geometry Geo Board Large Geoboard - The Geoboard is primarily used in the exploration and recognition of shapes, designs, spatial relationships, angles, fractions, area, perimeter, symmetry, and coordinates. It has 11 x 11 peg grid at one side and circular pegs on another side. The knobbed pins hold rubber bands (included) in place. Measure 27cm X 27 cm.