Applying professional-vision skills to classroom situations depends on knowledge about what matters in these situations. In an experiment with 85 biology pre-service teachers, we investigated a 90-min intervention combining both acquisition and application of knowledge about tutoring. The intervention started with an introductory text, followed by classroom video examples. Students who read a text on concrete tutoring strategies made more references to pedagogical concepts in their analyses than students who read about generic video observational guidelines. We conclude that combining a short, focused theoretical introduction and video analysis is a promising method to broadly anchor professional-vision training within teacher education. Display omitted •Effects of an initial intervention session on pre-service teachers' professional vision.•Pretraining improves the quality of subsequent observation of classroom videos.•Pretraining raises situational interest in video analysis tasks.