Innovation is a risky and difficult activity, fraught with false starts and failures, as ideas get turned into programmes, products and services. The task of taking promising ideas to a large scale is even more daunting than turning that idea into a prototype. Education is littered with promising but small-scale innovations that remain trapped on the locations where they were first developed. That is why these high impact social innovators matter so much. They can help us understand how to spread change even in apparently hostile conditions, with few resources, and sometimes in the face of opposition from entrenched interests. This book is about why these revolutions matter, what makes them possible, and how we can make many more happen, in their tens of millions to give more young people the chance to learn and to change their lives for the better.