This is truly the overarching fight of the last 100 years. And the easiest way to understand everything that has happened to K-12.

Maria Montessori started off working with learning-disabled children. She believed in working with children as she found them and making them better. It does not matter if you like or dislike any particular feature or method that she used. She was trying to liberate the child’s full intellectual capability. That's the spirit we need in all of our schools, call it by whatever name you wish.

John Dewey is a cramped, narrow-minded ideologue. He did not care whether children were on the low-end or the high end. He was going to make them all the same: good little socialists. Dewey’s whole agenda was one of limiting academic sensibilities and eliminating traditional content. He had a template in his mind and everybody was going to fit it. He was a friend of totalitarianism.

See article for a quick summary of the historical battle: 

http://www.educationviews.org/maria-montessori-vs-john-dewey/

Maria Montessori vs. John Dewey -- The Fight of the Century