Why genocides occur is a perplexing and complex question. Leanne Judson reports a strategy designed to help students think about perpetration and evaluate and propose explanations for perpetrators' actions. Students in a mixed ability class were given explanations of differing levels of complexity to evaluate, drawing on a wide range of complex materials about perpetrators as "real" people rather than simply "monsters". Students were also provided with explicit guidance to help them scaffold their arguments, in explanation or in evaluation of explanations. Results were positive, in terms of the quality of pupil work and in motivating pupils to take pride in their work.