Here's another one from the sci-fi realm: The Troika Incident by James
Browne III, late 60's or early 70's.
The School in Rose Valley, Grace Rotzel (1972?) about a school that continues
to this day, nearing 70 years old!
How Children Learn
The Underachieving School, both by John Holt (late 60's)
I Learn From Children, Caroline Pratt, late 60's
Thanks for compiling this!