The studies
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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.
4 of 46 studies
- Design
- Lottery study
- Grade bands
- 3–5, 6–8
- Subjects
- Reading and ELA, Social studies, Science
- Sample
- 2,310 applicants to 9 Colorado Core Knowledge charters
- Compared with
- Lottery losers who attended other schools
- Found
- About 16 percentile points higher in reading in grades 3–6; income gap closed at the one low-income school.
- Limits
- Charter schools, so curriculum and school model came together.
- Design
- Randomized trial
- Grade bands
- K–2
- Subjects
- Reading and ELA, Science, Social studies
- Sample
- 30 schools, nearly 3,000 students
- Compared with
- Business as usual
- Found
- Science reading comprehension up (0.18); smaller summer losses.
- Limits
- Overall district reading score not significant in the WWC review.
- Design
- Lab study
- Grade bands
- 6–8
- Subjects
- Reading and ELA
- Sample
- 64 seventh and eighth graders
- Compared with
- Students with less baseball knowledge
- Found
- Baseball knowledge, more than reading ability, predicted comprehension of a baseball text.
- Limits
- Small; disputed in later critiques.
- Design
- Correlation
- Grade bands
- K–2, 3–5
- Subjects
- Social studies, Reading and ELA
- Sample
- ECLS-K 2011 national data
- Compared with
- Less social studies time
- Found
- More social studies time linked to better reading; more ELA time was not.
- Limits
- Not causal.