This work shows a study about the influence of the role defended during the participation in a role-playing game about nuclear energy on the pre-service elementary science teachers’ scientific knowledge. 74 pre-service teachers participated in four role-playing games and a mixed approach was followed for data analysis, through a pre-test/post-test. The results suggest that the pre-service teachers who had to defend a role with a position against their personal point of view could achieve greater scientific knowledge learning. Furthermore, some limitations of this study are discuss.