Focusing on a group of African American third graders who attend a high-poverty urban school, I explore the structure-agency dialectic within contested spaces situated in a dialogically oriented science classroom. Contested spaces entail the moments in which the students challenge each other's and their teacher's science ideas and, in the process, construct agentic science selves. Drawing on sociocultural frameworks, I demonstrate the complexities of agency within contested spaces and the ways in which contested spaces shape and are shaped by agentic moves. Using an interpretive qualitative analysis, I found that contested spaces bubble up are maintained by dialogue, and simmer down over time. In this study, children exercised both individual and collective agency in negotiating science ideas with their teacher to shape the science classroom space in favor of their own meaning making. Using dialogicality as a resource and building on their own cultural resources, the children acted as a community of learners to challenge their teacher's science ideas and, in doing so, transformed the dialogic space within the classroom. This study highlights the tensions teachers face in choosing authentic meaning making within the limits of the school day and their own science knowledge. In addition, it demonstrates the importance of providing equitable learning spaces for African American children that offer them opportunities to agentically use their own ways of being as resources for learning and becoming in science. # 2015 Wiley Periodicals, Inc. J Res Sci Teach Keywords: equity; diversity; dialogic teaching; learning communities Schools and classrooms are culturally and historically situated spaces impacted by issues of class, race, gender, and power, as well as sites of conflict for and between teachers and students, ideas, values, and goals. In the last decade, teachers have faced the implications of the increased regulation of schooling, including instructional practices, the narrowing of the curriculum, and the pressures associated with frequent and multiple standardized measures of student achievement (Crocco & Costigan, 2007). This is particularly true in high-poverty urban schools that serve historically marginalized students. Because of increasing expectations related to student achievement, teachers often struggle to manage the demands of teaching within the limits of the school day. Furthermore, conflicts have always arisen between teachers and students in classrooms relative to teachers' attempts to manage or control students' actions and ideas. On the one hand, teachers have a curriculum to complete; on the other hand, students strive to make sense of their worlds through their experiences and the content of schooling. These contrasting goals often give rise to conflict, which can be problematic in classrooms. However, spaces of conflict The opinions, findings, conclusions, and recommendations expressed in this paper are those of the author and do not necessarily reflect the views of the NSF.