Within-Class Grouping: A Meta-Analysis

TLDR

The effects of within‑class grouping on student achievement and other outcomes were quantitatively integrated using two sets of study findings. The authors integrated two sets of study findings: one with 145 effect sizes comparing grouping versus no grouping on several outcomes, and another with 20 effect sizes directly comparing homogeneous versus heterogeneous ability grouping. Overall, within‑class grouping produced small positive effects on achievement (average effect sizes +0.17 for small‑group learning and +0.12 for homogeneous grouping), but variability was heterogeneous and effective practice requires adapting instruction methods and materials for small‑group learning.

Abstract

The effects of within-class grouping on student achievement and other outcomes were quantitatively integrated using two sets of study findings. The first set included 145 effect sizes and explored the effects of grouping versus no grouping on several outcomes. Overall, the average achievement effect size was +0.17, favoring small-group learning. The second set included 20 effect sizes which directly compared the achievement effects of homogeneous versus heterogeneous ability grouping. Overall, the results favored homogeneous grouping; the average effect size was +0.12. The variability in both sets of study findings was heterogeneous, and the effects were explored further. To be maximally effective, within-class grouping practices require the adaptation of instruction methods and materials for small-group learning.