For feedback loops, I found study groups to be very very useful in university. Reflecting on high school it seems weird they weren’t used more often.
After trying a problem on your own, taking your results and collaborating with peers is a one of the best ways to learn. Sometimes you have to assume the role of teacher and share your idea, which requires you to really understand it.
I know the fact that you meet essentially every kind of person in school is a good thing, but I never fit the mould of learning the way school taught, so providing more diverse ways of learning I think could be a big boon to education.
