Changes in participant structures in classroom environments are often examined in terms of their effects on student learning. In this study, we proposed a way of examining participant structures in terms of power. According to Wertsch (1998) "the emergence of new cultural tools transforms power and authority" (p. 65). When researchers or teachers introduce new tools into classrooms including new participant structures, they create the potential for transforming many relationships of power: between students and teachers, among students, and between students and the material being studied. Using data from a 6th-grade classroom involved in a science unit, we consider how these transformations of power play out. In considering the role of participant structures, we look at how a match between the participant structures and the structure of the discipline can positively affect these relationships of power.