This series of prisms demonstrates to the child the change in width (breadth), while the length remains constant. Practice with The Brown Stair indirectly prepares the child for concepts in plane geometry, area and volume. -- distributor website
Notes
The 5 brown prisms are of the same length (20cm.) but differ in height and depth. The largest stair is 20 x 10 x 10cm. scaling down 5 steps to the smallest stair 20 x 2 x 2cm