The Sensorial Materials have been given many names: Materialized Abstractions, Keys to the Universe, Paths to Culture. These multiple denominations are perhaps indicative of the enthusiasm the materials evoke in people who know them well. They are deceptively simple in appearance and totally satisfying to the developing child.

The reason for the success and popularity of these materials is that they allow the children to undertake such activities as all children undertake spontaneously. Given the opportunity, with or without specialized materials, children will sort things by size, shape, color, touch, sound, temperature and weight. They will grade from dark to light, and from large to small. The Montessori sensorial apparatus allows them to classify sensorial impressions in an organized, orderly and scientific manner. The Sensorial Materials are mathematically graded; they isolate one quality only, keeping the remaining characteristics identical and are limited in both scope and quantity. Moreover, they have a built in control of error. The Sensorial Materials allow for individual work and for repetition. This makes it possible for the children to abstract the concept made concrete in each piece of material, to name it, and to then apply it to the environment, thereby perceiving their universe with greater awareness. Because of the clarity of the concepts abstracted, the Sensorial Materials lay a solid foundation for Mathematics, Geometry, Geography, Botany, Art and Music. Being wide in scope, they invite the children to explore all the possibilities they have to offer. Thanks to the control of error inherent in the Sensorial Materials, the children acquire the habit of working independently, unafraid of making mistakes, becoming comfortable with the fact that errors are essential to the process of learning. And, incidentally, they establish a tendency towards intellectual honesty.