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Showing 7 verified claims · instruction, resources & composition
High-dosage tutoring — frequent (typically >=3 sessions/week), sustained, small-group or one-to-one instruction delivered during the school day by trained tutors — is among the most reliably effective interventions for raising student achievement, with consistent positive effects across dozens of randomized field experiments; effects are largest in early grades and for lower-achieving and lower-income students.
Systematic phonics instruction — explicitly teaching grapheme-phoneme correspondences in a defined sequence — improves early reading, especially decoding and word reading, with the largest benefits for younger children and for students at risk for or with reading disability; it is an essential component of effective beginning reading instruction.
Court-ordered school desegregation produced lasting improvements in Black students' educational attainment, earnings, and health, and contemporary school segregation is associated with wider racial achievement gaps — largely because segregation concentrates minority students in under-resourced, high-poverty schools, rather than through racial composition per se.
Delaying secondary-school start times (toward 8:30 a.m. or later) reliably increases adolescents' sleep duration and is associated with better mood, attendance, and some academic and behavioral outcomes; the sleep effect is well established and replicated, while the magnitude of downstream academic gains and the practical trade-offs (transport, scheduling) are more uncertain.
Substantial class-size reduction in the early grades (e.g., to 13-17 students, as in Tennessee's Project STAR) produces small-to-moderate short-term gains in student achievement, with larger benefits for low-income and minority students; long-term and at-scale effects are smaller, inconsistent, and contested.
The effects of grade retention are genuinely contested: rigorous regression-discontinuity studies of test-based retention find short-term achievement gains that typically fade, with conflicting evidence on later attainment — some find no effect on graduation, others find increased dropout and reduced attainment — while older observational research consistently links retention to higher dropout.