Walden schools is new to me. I do know that Montessori education
basically puts into practice this idea of the the self-directing child, who chooses freely what part of knowledge-ability it is up to. Both my sons had the Montessori elementary school and got their masters well enough.
(Montessori put into practice the musings about education of
Rousseau: Émile ou de l'Éducation. ( Emile or about Education?) Quite a good book to read, quite entertaining.)

Walden?

Montessori