Equity Issues in Collaborative Group Assessment: Group Composition and Performance

This study investigated the effects of group ability composition on group processes and outcomes in science performance assessments. Students in 21 eighth-grade science classes worked on science assessments first individually, then in groups, and finally individually again. Group composition had a major impact on group discussion quality and on student achievement. Groups with above-average students produced more accurate and high-quality answers and explanations about how to solve the test problems than groups without above-average students. As a result, below-average students who worked with above-average students showed higher achievement than did below-average students who worked without above-average students. High-ability students generally performed better when they worked in homogeneous groups than when they worked in heterogeneous groups. The fact that heterogeneous groups provide a greater benefit for below-average students than they impose a detriment on high-ability students is discussed.