Average test scores are higher when classes are sorted by skill, driven by large learning gains for high-skilled students and slightly lower scores for low-skilled students¶

Claim · All claims
Evidence · 1 study · causal r? · q2
Currency · newest study 2014 · checked against its sources 2026-10-20 (automated, 1 of 1 entry) · not reviewed by a person

Subclaims¶

q2 i? Overall test scores are higher when classes are sorted by skills because high-skilled students show large learning gains under sorting. → Elaine Allensworth and Takako Nomi 2014 q2 i? Low-skilled students have slightly lower test scores with sorting, and on average the gains for high-achievers offset the losses for low-achievers. → Elaine Allensworth and Takako Nomi 2014

Evidence¶

Elaine Allensworth and Takako Nomi 2014¶

Elaine Allensworth and Takako Nomi. (2014). Skill-Based Sorting in the Era of College Prep for All. University of Chicago Consortium on Chicago School Research. https://consortium.uchicago.edu/publications/skill-based-sorting-era-college-prep-all-costs-and-benefits

q2 · i? · causal · r?

The CCSR report compares Chicago Public Schools reforms that sorted algebra students by ability versus de-sorted them. It reports that sorting raises overall test scores, quoting that "test scores are higher when classes are sorted by skills," with no effect sizes printed in the release.

"Overall, test scores are higher when classes are sorted by skills due to large benefits for high-skilled students' learning gains. Low-skilled students have slightly lower test scores with sorting, while high-skilled students have substantially higher test scores."

Discussion¶

Related Claims¶

• Between- or within-class homogeneous ability grouping has a small negative effect on low-ability primary students but no effect on other students — the general claim this finding bears on, with the studies behind it
• How students are sorted into classrooms by skill level can affect their achievement as much as the content they are taught — related
• Sorting by ability affects grades and pass rates differently from test scores: high-skilled students' grades and pass rates decline while low-skilled students' grades improve — related
• Fish pond effects: above-norm students became more likely to fail algebra when their skills were low relative to classroom peers after sorting — related
• Algebra failure rates rose post-policy for above-norm students (~3 percentage points) but fell for below-norm students (~4 points); classroom environment and peer ability explained most of the above-norm rise but not the below-norm fall — related
• When classes are sorted by skill level, low-skilled students are at higher risk of being in disruptive classrooms, weakening their instructional environment — related
• Pre-policy, classroom average ability related positively to test scores but positively to failure, with effects strongest for high-ability students — related
• Below-norm students' algebra test scores improved despite having lower-skill peers post-policy, consistent with additional supports offsetting compositional decline — reports the opposite
• Quality of explanations is higher in groups containing above-average students than in groups without them — related