Controlling a complex system is rarely as effective as allowing it to self-organize: markets work better than planning committees; diverse ecosystems are more robust than monocultures. What would it mean to apply this idea to education?Our world is kept afloat by a massive, decentralized body of often unseen knowledge.This dark mass is made up of innumerable pieces of know-how accumulated by people mostly stumbling around, observing each other and the way things work. It's what's lodged in the h...