Since Montessori is a word in the public domain, it is possible for any individual or institution to claim to be Montessori. But an authentic Montessori classroom must have these basic characteristics at all levels:
Teachers credentialed in the Montessori philosophy and methodology for the age level they are teaching, who have the ability and dedication to put the key concepts into practice.
A partnership established with the family. The family is considered an integral part of the individual’s total development.
A multi-aged, multi-graded, heterogeneous grouping of students.
A diverse set of Montessori materials, activities, and experiences, which are designed to foster physical, intellectual, creative, and social independence.
A schedule that allows large blocks of time to problem-solve, to see connections in knowledge and to create new ideas.
A classroom atmosphere that encourages social interaction for cooperative learning, peer teaching, and emotional development.
The above is adapted from The American Montessori Society pamphlet titled, “It is necessary, It is Montessori.”