Five Common Misconceptions about Montessori Schools
The North American Montessori Teachers Association and John Chattin-McNichols, a professor at Seattle University, independently sought to identify misconceptions about Montessori education.  This list is derived from their work.

1. Montessori is only for the rich.
Misconception - Montessori began her work with poor children in the slums of Rome. The American Montessori movement began in the 1960s as a private pre-school movement, supported by tuition but it has grown. It has not received the public support it merits- the support that would allow it to serve many more poor children but it is offered in more than 250 public-school sites and at several Head Start centers.

2. Children in Montessori classrooms do whatever they want.
Misconception - Montessori education is based on the principle of free choice within limits of purposeful activity.

3. Montessori classrooms are too structured.
Misconception - Although the teacher is careful to make clear the specific purpose of each material and to present activities in a clear, step-by step order, the child is free to choose from a vast array of activities and to discover new possibilities.

4. Montessori classrooms discourage fantasy and stifle creativity.
Misconception - Teacher-directed fantasy play is rare among Montessori educators, but fantasy play initiated by the child is viewed by many as healthy and purposeful, depending on the child's health and stage of development.

5. Montessori classrooms push children too far too fast.
Misconception - Montessori education emphasizes allowing each child to develop at his or her own pace.

Source: CHILD Montessori School
http://www.childmontessori.com/misconceptions.htm