Open-mindedness is defined as one's willingness and ability to consider opposing beliefs and perspectives and give them a serious, impartial consideration by setting aside one's commitment towards one's own beliefs and perspectives. Learning to prepare and teach open-minded lessons is a crucial skill for student teachers because it fosters an atmosphere in which pupils feel free to express their own views and to learn about the views of others. The aim of this experiment was to examine which instructional strategy best supports student teachers' learning to prepare an open-minded citizenship education lesson. Therefore, participants (n = 176) processed an instruction on how to prepare an open-minded citizenship education lesson through learning by teaching on video, preparing to teach, or re-study (control condition), and as a post-test designed a lesson plan. We examined the completeness and accuracy of the explanations of the instructional content, feelings of social presence and arousal, open-mindedness levels, the completeness and accuracy of the lesson plans, and the conceptual knowledge of the instructional content. In addition, the lesson plans were graded on overall quality. Results showed that all participants scored higher on open-mindedness as measured with the Actively Open-minded Thinking scale after the experiment than before the experiment. Participants in the control condition prepared significantly more accurate and complete open-minded lessons than participants in the other two conditions, suggesting they have gained better understanding of the instructional content. There were no significant differences between the conditions on the other outcome measures.