This article details a multi-modal active learning experience to help students understand elements of social categorization. Each student in a group dynamics course observed two groups in conflict and identified examples of in-group bias, double-standard thinking, out-group homogeneity bias, law of small numbers, group attribution error, ultimate attribution error, and moral exclusion. Students individually wrote papers detailing their observations. The author then carefully structured students' small and large group discussions so students could present and compare their findings orally. Pretest-posttest analyses revealed that students had a more complete and accurate understanding of social categorization after participating in this assignment than they did after merely reading the relevant textbook chapter.