There are 250 to 300 public Montessori schools nationwide. American Montessori Society President Michael J. Dorer, an education professor at the College of St. Catherine in St. Paul, Minn., said creating more public schools would be the best way to break out of the upper-income niche that in some ways still limits the Montessori movement's growth.

Dorer said his college and several others train Montessori teachers, but there are not enough instructors with credentials to meet demand from the expanding number of Montessori schools. Some schools with the Montessori name don't have many, or any, Montessori- trained teachers. "Anyone can open a school and call it a Montessori school. There is no trademark on the name," Dorer said. "It's a real problem."

Valaida L. Wise, head of the Henson Valley school, graduated from what is now the Nora School. The small, private secondary school in Silver Spring shares some of the Montessori emphasis on putting students rather than teachers in charge of learning. That's what theorists generally mean by progressive education. Wise calls Montessori "progressive education on steroids."