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Version 1.2 – Updated June 2023

Within-class grouping


  • Influence: Within-class grouping
  • Domain: Classroom
  • Sub-Domain: Class composition effects
  • Potential to Accelerate Student Achievement: Likely to have a small positive impact
  • Influence Definition: Organizing students into small groups by interest, skill, ability, or various other factors within their regular classroom.


  • Number of meta-analyses: 3
  • Number of studies: 144
  • Number of students: 21,483
  • Number of effects: 209
  • Weighted mean effect size: 0.16
  • Robustness index: 3


Journal Title Author First Author's Country Article Name Year Published Variable Number of Studies Number of Students Number of Effects Effect Size
Conference paper Kulik USA Effects of inter-class ability grouping on achievement and self-esteem 1985 Inter-class ability grouping 78 0 78 0.15
Society for Research on Educational Effectiveness Puzio & Colby USA The Effects of Within Class Grouping on Reading Achievement: A Meta-Analytic Synthesis 2010 Within class grouping in reading 15 5,410 28 0.22
Conference paper Lou, Abrami, Spence, Poulsen, Chambers, & d'Apollonia Canada A Meta-analysis of the effects of homogeneous versus heterogeneous group ability composition on student achievement: Looking at the "best" evidence. 1996 Within class grouping 51 16,073 103 0.17
TOTAL/AVERAGE 144 21,483 209 0.18
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