DOES CLASS SIZE MATTER?

By Diane Whitmore Schanzenbach, Northwestern University

Executive Summary

Public education has undergone major reforms in the last 30 years with the rise in highstakes

testing, accountability, and charter schools, as well as the current shift toward

Common Core Standards. In the midst of these reforms, some policymakers have argued

that class size does not matter. This opinion has a popular proponent in Malcolm Gladwell,

who uses small class size as an example of a “thing we are convinced is such a big

advantage [but] might not be such an advantage at all.”

These critics are mistaken. Class size matters. Research supports the common-sense

notion that children learn more and teachers are more effective in smaller classes.

This policy brief summarizes the academic literature on the impact of class size and finds

that class size is an important determinant of a variety of student outcomes, ranging from

test scores to broader life outcomes. Smaller classes are particularly effective at raising

achievement levels of low-income and minority children.

Considering the body of research as a whole, the following policy recommendations

emerge:

 Class size is an important determinant of student outcomes, and one that can be

directly determined by policy. All else being equal, increasing class sizes will harm

student outcomes.

 The evidence suggests that increasing class size will harm not only children’s test

scores in the short run, but also their long-run human capital formation. Money

saved today by increasing class sizes will result in more substantial social and

educational costs in the future.

 The payoff from class-size reduction is greater for low-income and minority

children, while any increases in class size will likely be most harmful to these

populations.

 Policymakers should carefully weigh the efficacy of class-size policy against other

potential uses of funds. While lower class size has a demonstrable cost, it may prove

the more cost-effective policy overall.

Click here to read the full report.