By Emily Ayscue Hassel and Bryan C. Hassel
Adult-led, small-group tutoring adds huge learning growth for students, even in small doses weekly. But finding the right group size is tricky. Too large, and learning impact per student declines. Too small, and the number of students reached plummets—pushing down learning growth class-wide.
It’s easy to guess that 1:1 is ideal, or that that the group size with the highest “effect size” in research is best.
Here’s a different take: Aim for the maximum average learning impact across each classroom, team, or school. Calculating the average means that any student left out of tutoring gets “0” extra learning growth.
These are tutoring effect sizes in one analysis*, converted into “years of learning” using one common method:
Extra Years of Learning Per Student Tutored, by Group Size:
- 1 Student: 1.5 Years
- 2 Students: 1.2 Years
- 3 Students: 1.6 Years
- 4 Students: 1.6 Years
- 5 Students: 1.2 Years
Read more, because this is the misleading part: You might conclude that 1:1 is best, or 1:3, or 1:4, because students lucky enough to be in one of these groups make a lot of learning growth.
But what happens if we add a zero effect for students not receiving tutoring? For example, suppose five students need tutoring, but only one group slot is available. If you use 1:1, only one student gets the extra 1.5 years from the table above—the other four get zero. So, the average across five students is 0.30 years. Larger groups now look better:
Average Extra Years Learning Across 5 Students, by Group Size:
- 1 student tutored, 4 not: .30 Years
- 2 Students tutored, 3 not: .48 Years
- 3 Students tutored, 2 not: .96 Years
- 4 Students tutored, 1 not: 1.28 Years
- All 5 Students tutored: 1.20 Years
Group sizes of four to five achieve the maximum average effect on student learning across all students. Apply that to a whole class, team, or school, and the benefit is huge. While four to five might not seem like a big difference from three to four, 29 percent more students would be reached in a school that tutors with groups averaging four to five students instead of three to four, on average. Rounding down cuts out large percentages of students in a class, or school—and then we have to ask: who are you leaving out?
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Related:
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Stop Wasting Student Teachers’ Time and Money
Can You Add Tutoring Time for Free?
*Nickow, A., Oreopoulos P., & Quan, V. (2020). The impressive effects of tutoring on preK-12 learning: A systematic review and meta-analysis of the experimental evidence. Cambridge, MA: National Bureau of Economic Research. Calculation for groups of 3 excludes a small number of outlier studies; we have found eliminating outliers with likely intervening variables is important in maximum average analyses.