Creating concept maps is considered to be a powerful means for learning. It requires students to systematically organize and integrate their knowledge, which can foster meaningful learning. However, students scarcely spontaneously engage in the (meta)cognitive processes necessary for effective knowledge integration, such as reflection, which can hamper the effectiveness of concept mapping for learning. This study explores the effect of additional support that stimulates reflection by means of expert examples, reflection prompts, and classroom discussion. First-year technical vocational students (N = 144, M[subscript age] = 17.5 years) studied electricity-related topics in an online learning environment and created concept maps about their knowledge. Students' concept maps were supplemented with either (1) no support (control condition), (2) an expert example (a combined concept map, containing their own and an expert example concept map, with differences highlighted), (3) an expert example and reflection prompts students had to process individually, (4) an expert example and reflection prompts students had to process individually after a teacher-guided classroom discussion. Students in the classroom discussion condition showed higher learning gains compared to all other conditions. This can be explained by the quality of their reflection, which proved to be a significant predictor of learning gain.