The studies
Reviewed · 1 min read
Every grade on this site rests on the studies in this table. Each row says what kind of study it was, who was studied, what it was compared with, what it found, and where it falls short. Filter by grade band, subject, design or principle.
How to read the design column, and why a correlation never earns a grade, is explained on How we grade the evidence.
This is the seed of a larger database. The plan is to add every randomized trial of a classroom practice in K–12, with the same columns, so that a reader never has to go to a second site to check a claim. New studies are logged monthly and reviewed quarterly; see Keeping it current.
5 of 46 studies
- Design
- Randomized trial
- Grade bands
- 9–12
- Subjects
- Math
- Sample
- About 2,600 and 2,700 Chicago 9th and 10th graders, two trials
- Compared with
- Business as usual
- Found
- Math scores up 0.18 to 0.40 SD; effects lasted into later years.
- Limits
- High school math only; one city.
- Design
- Comparison study
- Grade bands
- K–2, 3–5, 6–8
- Subjects
- Reading and ELA, Math
- Sample
- Over 6,800 students across three years
- Compared with
- Students not tutored, often getting other small-group help
- Found
- Reading up 0.04 to 0.09 SD; no average effect in math or grades.
- Limits
- Many sessions before or after school; program changing as it scaled.
- Design
- Trend data
- Grade bands
- 3–5
- Subjects
- Reading and ELA, Math
- Sample
- 4th graders, state results
- Compared with
- Other states, demographics-adjusted
- Found
- First in the nation in 4th grade reading and math after adjustment; 49th in reading in 2013.
- Limits
- Not causal; many reforms at once.
- Design
- Meta-analysis
- Grade bands
- K–2, 3–5, 6–8, 9–12
- Subjects
- Reading and ELA, Math
- Sample
- 89 randomized trials
- Compared with
- No tutoring
- Found
- 0.29 SD average; largest with teachers or aides, early grades, 3+ days a week, during school.
- Limits
- Mostly pre-pandemic, smaller programs.
- Design
- Review or practice guide
- Grade bands
- K–2, 3–5, 6–8
- Subjects
- Reading and ELA, Math
- Sample
- Review of progress-monitoring studies
- Compared with
- —
- Found
- Achievement improved when teachers used progress data to change instruction; collecting it alone did little.
- Limits
- Mostly special education settings.