The Brown Stair is a Montessori material used in the sensorial area of the classroom to develop visual discrimination, size comparison, and coordination skills. It consists of a set of ten wooden prisms, all the same length but varying in height, width, and depth.

The Brown Stair set includes ten rectangular prisms made of wood, usually in shades of brown or natural wood color. The prisms are identical in length (typically 20 centimeters), but their height, width, and depth vary in incremental proportions. Students work with the Brown Stair by arranging the prisms in a stair-like formation from largest to smallest or vice versa. They learn to observe and differentiate the dimensions of each prism to identify the correct order and establish a sense of relative size. Manipulating the wooden prisms requires careful handling and control. Students practice precise movements and develop hand-eye coordination as they carefully place and align each prism in the correct order.

The Brown Stair provides opportunities for children to refine their senses, develop spatial awareness, and foster critical thinking skills through hands-on exploration and manipulation of the prisms.