The Broad Stair or Brown Stair consists of 10 hardwood prisms ranging from 1 X 1X 20cm to 10 X 10 X 20 cm.
Lacquered to a brown sheen.
The wood prisms demonstrate to the child the change in the width (breadth), while the length of 20 cm, remains constant. Further practice with the broad stair indirectly prepares the child for concepts in plain geometry.
