In this study, a lesson model related to the phenomenon of the rusting of iron was developed to confirm the effect of modeling by drawing on the understanding of chemical reactions. The model was applied in the non-science course “Science study (chemistry)” classes comprising third-year undergraduate students in Tokyo Gakugei University. Students constructed images of the rusting of iron, in addition to attending lectures with frequent discussions, without any prior written communication to students, as well as taking notes, and the students completed the subsequent process of drawing as well as its explanation. Students drew pictures with their own images and explained their drawings appropriately as per their own understanding of chemical concepts and the phenomenon at hand. By the evaluation of the lesson model via the lesson of an “activated complex” as a representative of the model by the process of drawing and self-explanation, as well as an intelligibility test, students could understand chemical concepts and images of the rusting of iron by actually drawing, i.e., the task of drawing could strengthen the student’s explanatory ability and intelligibility about the rusting of iron; in particular, it was effective for intelligibility even for students who obtained a low score of 0 points, besides the limitation of the effect on reinforcement of explanatory capability of the phenomenon for the 0 points score students, suggesting that learning with imaginative thinking and behavior is imperative for students to understand chemical reactions by evaluation.