Cooperation among students in a classroom setting allows for different individuals to blend their abilities to achieve goals set forth by the teacher. Collaboration, problem solving, conflict resolution, and working together are all important life skills, but questions remain about exactly how to group students. For example, it is not known if students should be grouped by ability, biological sex, interest, age, or intelligence, etc. Furthermore, it is not known if students should be grouped homogeneously or heterogeneously by achievement while participating in cooperative learning. It is this question that this study attempts to answer. 2 | BACKGROUND People working together cooperatively is not a new concept, just as it is not a new idea for teachers. In the early 1900s, John Dewey expressed the idea that the role of an educator was to prepare students for democratic citizenship by submerging students in real-world problem solving using collaboration and their imagination (as cited in Benson et al., 2007). There was a shift in American education away from collaborative work and into interpersonal competition in the late 1930s. This shift, later described as Darwinism in the classroom, then shifted yet again so that classrooms were influenced by John Locke (Johnson & Johnson, 1989). This did not change until the 1970s when cooperative learning had a huge emphasis from researchers, and in the 40 plus years since cooperative learning has been tested and proven as a useful learning tool in numerous studies (