This article explores the case of a Vietnamese teacher whose conception of teaching changed greatly following a short but intensive series of lessons based on the Japanese experiences with atomic bombs. The following three issues are considered: 1) what types of efforts teachers should make to increase the depth of their lessons, on the basis of children's reality of learning; 2) what kinds of support teachers require from colleagues, including external resource persons; and 3) how school management should be organized to practise peace education. (Contains 2 figures.)