This article analyses the classroom dialogues of Norwegian lower secondary students as they discuss the causes and implications of the July 22, 2011 terrorist attack, the most significant act of extremism in Norway’s modern history. Drawing on an activity designed to explore causation and prevention, the study evaluates the quality of group discussions in terms of their dialogic and substantive content. The findings show that while students showed high levels of engagement and adherence to dialogic practices, most exchanges remained non-critical, with limited depth in exploring the interrelations among causes. The study identifies variations in students' causal understanding and highlights the predominance of individual-related explanations over societal factors, reflecting a depoliticized approach to teaching the event. It also examines how students navigated complex issues, including ideological influences and the role of institutions. The findings contribute to understanding the pedagogical challenges and opportunities of addressing difficult history and fostering critical historical consciousness in schools.