My children attended Montessori schools, and it really is a wonderful system. I would really like to see an extension of this learning method up through high school --- the closest thing I'm aware of was a school I attended in Mississippi for a couple of years --- classes were divided between academic and social, social classes (homeroom, phys ed, social studies, &c.) were attended at one's age, while academic classe…
I had a good impression of "Montessori" from hearing that Larry/Sergey/Bezos went to one. When I put my kid in it at 3 years old, he hated it. As I looked into it more, it seems to me that it is actually very rigid, with kids being able to play with just a small set of toys that don't really exercise their creativity, and with little opportunity for group play. We switched him to a Reggio Emilia school where the kids…
The rest of the time had loose guidelines on what to do (like you should read X pages of any book in the library) or you were free to do/play with what you wanted once that stuff was done.
We were largely encouraged to do things in a group. I think the only place to even sit alone if you wanted was the book nook, everything else was communal tables.
I really enjoyed it, and was ahead to the point of being bored when I switched to public schools. I tried for like a week in 5th grade and they were covering geographic features I'd already done back in 2nd or 3rd grade (archipelagos and islets and what not).