In this study, we examined the effectiveness of "role-play materials" in which students are assigned roles in the classroom and have to deal with problems that relate to those roles. Specifically, we developed a teaching material, "Let's decide the price of pizza," for third graders in junior high school, and analyzed the contents of worksheets and questionnaires. The study found that "role-play materials" give students a better sense of reality than textbooks and they can easily have discussions based on various values that are not limited to mathematics.