While the sine qua non of Montessori is the philosophy, Montessori classrooms around the world are recognizable by their uniform sets of core materials. Teachers are trained in a sequential presentation of these materials in each area of the curriculum (practical life, sensorial, language, math and geography.) Montessorians speak always of the manipulative nature of the materials. Dr. Montessori is famous for saying that "Nothing is in the mind that is not first in the hand."
Dr. Montessori's work recognized early the still current science of links between sensory-motor or perceptual-motor exploration and cognition. Montessori manipulatives teach seemingly abstract concepts through concrete materials. They allow children to explore concepts at the Montessori 3 - 6 age that might otherwise be taught in elementary school.
