Addressing a need to prepare the next generation of scientists to effectively engage in adversarial science communication, the present study examines a group of undergraduate science students from a Canadian university who, after receiving expert instruction, participated in classroom debates about science controversies recently politicized in the Canadian social media (e.g. the flat Earth, genetically-modified foods, and human overpopulation). Our research questions were: (1) What emotions were experienced and how were these managed by students while participating in classroom debates? (2) How did students' emotional management influence their debate performance? A video-based micro-ethnography revealed that more than half of the students (16/28) experienced feelings of stress and nervousness when engaging debaters with opposing/disagreeing views. Although some were able to manage these emotions, others were unable to feel relaxed, which negatively influenced their debate performance. These latter students' initial confidence and preparation were undermined by their felt anxiety, leading to rhetorically weak and error-filled performances that went against their expectations. Highlighting the complexity of pedagogically promoting student development of communicative competence in adversarial social contexts, our findings reveal a need for science communication instructors to find ways to effectively prepare science students to manage their own emotions.