Teaching quality and socioeconomic achievement gaps: International evidence from two complementary processes

The association between teaching quality and socioeconomic disparities in student achievement remains underexplored, with existing studies offering competing perspectives. Two main hypotheses guide this debate. The differential effectiveness hypothesis suggests that certain teaching practices disproportionately benefit students depending on their socioeconomic background. In contrast, the inequality of educational opportunity hypothesis focuses on disparities in access to high-quality teaching across schools serving different populations. Drawing on TIMSS 2019 data from 46 education systems, we tested these hypotheses using mediation and moderation analyses. Our findings provide support for the inequality of opportunity perspective: in several countries, higher classroom discipline and instructional clarity partly mediate the association between classroom socioeconomic composition and achievement. By contrast, we find limited evidence for differential effectiveness, as neither instructional clarity nor classroom discipline consistently moderated the relationship between individual SES and achievement.