Here I discuss an empirical research study that investigated history teachers’ beliefs about ethical judgments when teaching history, and the relationship between the ways teachers approached ethical issues, questions, and judgments when teaching about Japanese Canadian Internment (JCI), a difficult event in Canadian history, and their students’ written responses. Among the history teachers focused on in the study, there was a large gap between what they believed about ethical judgments and how they actually approached them in the classroom, which impacted how students responded to JCI. This “knowing-doing” gap in teachers’ approaches to ethical judgments has important implications for teaching students about difficult events in history.