Each Montessori class, from toddlers through high school, operates on the principle of freedom within limits. Every program has its set of ground rules which differs from age to age, but is always based on core Montessori beliefs-respect for each other and for the environment.
Children are free to work at their own pace with materials they have chosen, either alone or with others. The teacher relies on his or her observations of the children to determine which new activities and materials he may introduce to an individual child or to a small or large group. The aim is to encourage active, self-directed learning and to strike a balance of individual mastery with small group collaboration within the whole group community. 
The three-year-age span in each class provides a family-like grouping where learning can take place naturally. More experienced children share what they have learned while reinforcing their own learning. Because this peer group learning is intrinsic to Montessori, there is often more conversation-language experiences-in the Montessori classroom than in conventional early education settings. 
The Montessori Group