The use of the materials is based on the young child's unique aptitude for learning which Dr. Montessori identifies as the "absorbent mind". In her writing she frequently compares the young mind to a sponge. It literally absorbs information from the environment. This process is particularly evident in the way in which a two-year old learns her native language, without formal instruction and without the conscious, tedious effort which an adult must make to master a foreign tongue. Acquiring information in this way is a natural and delightful activity for the young child who employees all her senses to investigate her interesting surroundings.

Since the child retains this ability to learn by absorbing until she is almost seven years old, Dr. Montessori reasoned that her experience could be enriched by a classroom where she could handle materials which would demonstrate basic educational information to her. Over 80 years of experience have proven her theory that a young child can learn to read, write and calculate in the same natural way that she learns to walk and talk. In a Montessori classroom the equipment invites her to do this at her own periods of interest and readiness.

Dr. Montessori always emphasized that the hand is the chief teacher of the child. In order to learn there must be concentration, and the best way a child can concentrate is by fixing her attention on some task she is performing with her hands. (The adult habit of doodling is a remnant of this practice.) All the equipment in a Montessori classroom allows the child to reinforce her casual impressions by inviting her to use her hands for learning.