Journal of the Learning SciencesPublication details, including instructions for authors and subscription information:

Although many cooperative learning methods advocate grouping students heterogeneously in order to maximize the diversity of perspectives, skills, and backgrounds, past research shows that heterogeneous grouping generally benefits low-ability students but does not necessarily benefit high-ability students. This study investigates the effects of group ability composition (homogeneous versus heterogeneous) on group processes and outcomes for high-ability students completing science performance assessments. High-ability students working in homogeneous groups uniformly performed well, and high-ability students in some heterogeneous groups performed as well as high-ability students in homogeneous groups; but high-ability students in other heterogeneous groups did not perform as well. The quality of group functioning served as the strongest predictor of high-ability students' performance and explained much of the effect of group composition.

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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.

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