No Relationship Between High School Class Size and Improved Student Performance

VANCOUVER—Despite popular misconceptions, there’s no relationship between high school class size and improved student performance on standardized tests, finds a new study released today by the Fraser Institute, an independent, non-partisan Canadian public policy think-tank.

“When class sizes increase, we immediately hear claims that student performance will suffer, but there’s no clear evidence smaller high school classes produce better student performance as measured by standardized tests,” said Derek J. Allison, professor emeritus of education at the University of Western Ontario, Fraser Institute senior fellow and author of Secondary school class sizes and student performance in Canada.

The study, which compared average provincial class sizes and test scores from the OECD’s Programme for International Student Assessment (PISA), found that in 2015 (the latest year of comparable data) Saskatchewan had the smallest average secondary school class size (22.6 students) among all 10 provinces but the lowest test scores in all three PISA subjects—reading, math and science.

Conversely, Quebec, which had the largest average class size (30.1 students) among provinces, had the highest math scores. Alberta, which had the second-largest class size (28.5 students), had the highest science scores while British Columbia (25.4 students) had the highest reading scores.
And Ontario, which had the smallest class size (24.8 students) among the four largest provinces, had the lowest test scores in all three PISA subjects among those four provinces.

Because it’s expensive for any province to maintain smaller class sizes, the money might be better spent on other educational initiatives aimed at improving student performance.

“If policymakers are serious about improving student performance, they should understand what the evidence actually says about class size and focus money in areas that can actually produce results,” Allison said.

The Fraser Institute is an independent Canadian public policy research and educational organization with offices in Vancouver, Calgary, Toronto, and Montreal and ties to a global network of think-tanks in 87 countries. Its mission is to improve the quality of life for Canadians, their families and future generations by studying, measuring and broadly communicating the
effects of government policies, entrepreneurship and choice on their well-being. To protect the Institute’s independence, it does not accept grants from governments or contracts for research.