- Low ability students who worked with high ability students performed significantly better than did low-ability students who worked with med-high, low-medium, or low-ability students.
- Group ability composition had a major impact on all performance and process variables.
- High ability students generally performed better when they worked in homogeneous groups than when they worked in heterogeneous groups. However the composition of heterogeneous groups was not a factor in high-ability student’s performance.
- Students at all ability levels benefit from working with high ability students, but dilemma: The performance of high-and low ability students cannot be optimized at the same time!
- Group composition must be taken into account when interpreting and comparing scores of different students, classrooms or schools.
- Heterogenous groups privde a greater benefit for below-average students than they impose a detriment on high-ability students.