10 Research Clusters

Teacher quality is the single most important school-based determinant of student achievement.

Intensive early childhood programs show high long-run returns, but modern scaled-up programs face a persistent fadeout problem.

Class size reduction produces positive effects in early grades, but is expensive and vulnerable to general equilibrium effects at scale.

Targeted school funding increases improve long-run adult outcomes, especially for low-income students. The debate has shifted from whether money matters to how it is spent.

Urban 'No Excuses' charter schools produce large, replicable gains. Non-urban charters and large-scale voucher programs often show null or negative effects.

Systematic, explicit phonics instruction is the scientifically validated foundation of early reading. The 'Reading Wars' have a clear empirical winner.

High-dosage tutoring is one of the most effective and reliably replicable interventions in K-12 education, with average effect sizes of d = 0.37.

Universal SEL programs reliably improve achievement and behavior. Targeted psychological interventions (grit, growth mindset) show weak effects at scale.

Family background and neighborhood poverty are primary drivers of educational inequality. High-quality schools can significantly mitigate, but not eliminate, these effects.

High-performing education systems share selective teacher preparation, equitable funding, and centralized curricula — but translating these features to the US context is deeply challenging.