Why Does Teacher Training Make a Difference in Math Scores?

High‑quality teacher training is a key lever to boost math performance from preschool to high school. Researchers pooled data from 20 studies that examined professional development (PD) programs for in‑service teachers, including those teaching students with disabilities or at risk. On average, PD produced a positive effect on student math outcomes (g = 0.34), though the impact varied widely, ranging from -0.20 to 5.83.

The team also tested whether factors such as grade level, delivery format (online vs. face‑to‑face), PD focus, number of training days, or inclusion of special‑needs students moderated the effect. None of these moderators showed a significant link, indicating that simply providing PD already makes a difference.

The authors recommend refining PD programs—making them more hands‑on and directly tied to classroom practice—and further investigating how teacher learning translates into student achievement. In short, investing in teachers’ professional growth is a solid strategy to raise young people’s math skills.

The meta‑analysis calculated the standardized effect size g, allowing comparison across studies with different measurement scales. A g of 0.34 represents a small‑to‑medium effect per Cohen's conventions. The wide prediction interval (‑0.47 to 1.15) signals high heterogeneity, likely stemming from methodological differences, school contexts, and intervention types.

The tested moderators (grade level, format, focus, PD days, inclusion of students with disabilities) were not significant, but this does not rule out other unexamined variables—such as coaching quality, alignment with curriculum, or administrative support—that might affect outcomes.

One theoretical explanation draws on Shulman's knowledge transformation model, where PD must convert declarative knowledge (theory) into procedural knowledge (practice). Additionally, Bandura's self‑efficacy theory suggests that teachers confident in their pedagogical skills are more likely to adopt innovative strategies, benefiting students.

Future research should employ more rigorous experimental designs, incorporate process measures (e.g., classroom observations), and assess long‑term impacts to clarify how professional development translates into sustained student learning.