"Montessori education is an educational approach developed by Italian physician and educator Maria Montessori and characterized by an emphasis on independence, freedom within limits, and respect for a child?s natural psychological, physical, and social development. Although a range of practices exists under the name "Montessori", the Association Montessori Internationale (AMI) and the American Montessori Society (AMS) cite these elements as essential: Mixed age classrooms, with classrooms for children ages 21⁄2 or 3 to 6 years old by far the most common... Student choice of activity from within a prescribed range of options... Uninterrupted blocks of work time, ideally three hours... A constructivist or "discovery" model, where students learn concepts from working with materials, rather than by direct instruction... Specialized educational materials developed by Montessori and her collaborators... Freedom of movement within the classroom... A trained Montessori teacher.