In this study, we created a three-dimensional (3D) model of a simplified direct current (DC) motor and used it to explain the mechanism of actual DC motors to junior high school science classes. We implemented a questionnaire for students before and after the presentation of the model. Before the presentation, many students were not confident about explaining the mechanism of a DC motor based on Fleming's left-hand rule. Then, we showed the stereoscopic display of our DC motor model from various viewpoints and explained the application of Fleming's left-hand rule. The results of the questionnaire suggested that students gained confidence in explaining the application after viewing the stereoscopic display. It was suggested that the change of viewpoint in the stereoscopic display was effective in improving their understanding.