Brown Stairs 5 stepsMade exclusively for toddlers. This series of prisms demonstrates to the child the change in width (breadth), while the length of 20 cm remains constant. Further practice with the Broad Stair indirectly prepares the child for concepts in plane geometry, area, and volume. The hardwood prisms are crafted in precise progressions from 2 x 2 x 20 cm (thin) to 10 x 10 x 20 cm (thick).