- Low-ability students interacted more and completed the instruction more efficiently in heterogeneous than in homogenous groups.
- High ability students completed the instruction more efficiently than in heterogeneous groups.
- Cooperation was significantly related to achievement for heterogeneous ability groups, but not, for either homogenous high- or low-ability students.
- A significant and positive overall correlation was found between cooperative interaction and achievement. However, further analysis indicated that the relationship is mediated in part by ability grouping.
- It seems that the quality of the interaction is mediated by both ability ad group composition.
- Ability grouping appears to affect the quality and quantity of the interaction.
- IN larger groups, individual members may have little influence over group behavior, but in dyads members may form a coalition and individual effort may be more highly valued.
- Group composition has important implications, especially when learning gains for one group are achieved at the expense of even small achievement losses for another.
- Heterogeneous grouping provides a supportive learning environment for low-ability students, but that the benefit is partially offset by reduced efficiency for the most able students.