Class Size and Eighth-Grade Math Achievement in the United States and Abroad
Using data from the Third International Math and Science Study (TIMSS), we examine the relationship between class size and eighth-grade math achievement in Australia, Canada, France, Germany, Hong Kong, Korea, Iceland, Singapore, and the United States. Class sizes tend to be greater and more homogenous in centralized education systems compared with those in decentralized systems. The United States seems to be unique among the countries in our study. After controlling for possible confounding characteristics of the teacher, school, and classroom, in no other country than the United States did we find a beneficial effect of small classes. Contrary to our expectations, we also found little evidence that smaller or larger classes differ in the amount of curriculum taught or in the instructional practices of teachers. Except for the case of Hong Kong, neither curricular coverage nor instructional practices mediates the relationship between class size and math achievement.