Understanding the effect of differences in prior knowledge on middle school students' collaborative interactions and learning

We investigated how the level of variance in students' prior knowledge may have influenced their collaborative interactions and science learning in small groups. We examined learning outcomes from 102 groups from seven science teachers' classes and discourse from two contrasting groups: Homogeneous versus heterogeneous. We examined individual and group outcomes using hierarchical linear modeling (HLM) to explore the effect of membership in a homogeneous or heterogeneous group on students' learning. We then used social network analyses (SNA) to identify any differences in interaction patterns between the two contrasting groups as they conducted multiple compost simulations. Finally, we examined students' discussions in these groups to better understand their interactions. In our HLM analysis, we found that students in homogeneous groups made significantly greater learning gains than students in heterogeneous groups. The SNA and thematic analysis of the discussions in our contrasting groups helped us identify that the interactions in the homogeneous group were more distributed, while the interactions in the heterogeneous group were more centralized around the member with the greatest prior knowledge, and that these patterns were stable over time. We also found that the students in the homogenous group engaged in richer discussions that were more supportive and built upon one another's ideas, which may have influenced their group and individual learning outcomes. While our findings indicate that students in homogeneous groups learn more and collaborate better, we discuss how some heterogeneity may be helpful, and group formation should focus on avoiding extreme cases of heterogeneity and provide students with scaffolding for collaboration.