This study examined the effect of class sizes on differences in the trajectories of elementary school students' long-term Japanese language achievement by analyzing panel data composed of standardized achievement test scores at five points from around the end of first grade to around the end of fifth grade. The data for 103 schools, 162 classes,…

Class size reduction policies have been widely implemented around the world in recent years. However, findings about the effects of class size on student achievement have been mixed. This study examines class size effects on fourth-grade mathematics achievement in 14 European countries using data from TIMSS (Trends in International Mathematics and…