Government advice in relation to 'countering violent extremism' (CVE) in English schools requires teachers to identify students 'at risk' of radicalisation whilst also encouraging them to facilitate open classroom discussions of controversial issues. Data collected in seven schools illustrate how teachers are responding to this advice and illuminate three tensions within 'controversial issues' pedagogy. First, we discuss the tension between depth and coverage in case studies, which risks treating history as parable. Second, we identify a problem with finding a genuinely open ethical dilemma to discuss, which entails the risk of adopting a hypocritical stance in the classroom. Third, we identify a tendency to perceive school as the antidote to undesirable social attitudes. The teachers' responses highlight the usefulness of framing certain issues as 'controversial' but also illustrate how difficult this can be in practice, especially in the context of CVE, which is perceived by many as a controversial policy.