Concerned by the growing tendency of politicians and press to revive the moral balance-sheet approach to British imperial history and by some evidence of its resurgence in schools, Alex Benger set about devising a framework which would keep pupils' analysis rigorously historical, rather than moral and politicised. In this article, he sets out his disciplinary and ethical grounds for doing this. He then explains how he built a set of analytical concepts to give his Year 9 pupils' enquiry a disciplinary framing. Drawing on Catherine Hall's argument that colonial diversity was tempered by the existence of similar dynamics of colonial power and inequality, Benger devised analytical concepts which allowed his pupils to discern patterns across colonial contexts.