How does class size vary around the world?

Elisabeth Villoutreix
Communications Officer, Directorate for Education

Class size is a hotly-debated topic and continues to be at the forefront of the educational and political agenda in many countries. Smaller classes are favored by parents and teachers alike. But they come at a price, countries can spend their money only once and money spent on smaller classes can’t be spent on better teacher salaries, more instruction time, better opportunities for the professional development of teachers…

So what’s the magic formula? What is the  ideal class size? Is smaller necessarily better?

The latest issue of Education Indicators in Focus shows that at the lower secondary level  among all OECD countries with comparable data, the average class size varies from 20 students or fewer in Denmark, Estonia, Finland, Iceland, Luxembourg, Slovenia, Switzerland (public institutions) and the United Kingdom, to more than 34 students in Korea. The contrast is even more striking in other G20 countries; in China, for example, the number of students per class reaches the 50 students mark.

Class size, together with students’ instruction time, teachers’ teaching time and teachers’ salaries, is one of the key variables that policy makers use to control spending on education. Between 2000 and 2009, many countries invested additional resources to decrease class size; however, student performance has improved in only a few of them.

Apart from optimising public resources, reducing class size to increase student achievement is an approach that has been tried, debated, and analysed for several decades. Some countries like Finland favour smaller class sizes (20 students of fewer) and are among the most successful countries in the PISA study. However, other countries like Korea have much bigger classes (34 students and over) but also feature at the top of the PISA ranking. What other variables than class size may explain the success of countries like Korea?

Findings from the OECD Programme for International Student Assessment (PISA) suggest that systems prioritising higher teacher salaries over smaller classes tend to perform better, which confirms research showing that raising teacher quality is a more effective measure to improve student outcomes.

For more information
On this topic, visit:
Education Indicators in Focus: 
On the OECD’s education indicators, visit:
Education at a Glance 2012: OECD Indicators: 
On the OECD’s Indicators of Education Systems (INES) programme, visit:
INES Programme overview brochure
Chart source: Education at a Glance 2012: OECD Indicators, Indicator D2 (www.oecd/edu/eag2012)

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