The curriculum works from the large concept to the more refined. Concepts are introduced through hands-on materials which encourage and engage the child and assist in a understanding of concepts before they are committed to memory. As the child enters the next phase, from 9 to 12, the world is an ever-expanding place. The horizons of the imagination increase and concepts may be presented and abstracted with fewer manipulative materials. The students' hands-on activities broaden in scope and include practical application outside the classroom.
Projects become more involved and diverse in nature.
Because the child goes through these various stages, Montessori classrooms are organized into three year age groupings. This allows a greater flexibility in meeting each child's individual needs. The Montessori approach to education was reintroduced in the United States around 1960. By today's estimates, there are at least 4,800 Montessori schools in the country, serving some 400,000 children from infancy through secondary levels, in both public and private settings. Special training is required for becoming a Montessori teacher.