ABSTRACT
We might be able to design a very effective intervention in a school that can be sustained over time with new staff and new students, and even over time with the same students as they develop through the school. But can this intervention be made to work with more and more schools? It is not much use if it is only workable with one school or a small set of schools because in most countries the children for whom we want schools to be more effective are not just in one or a small set of schools. Can the intervention be scaled up?
