How Does Class Size Vary Around the World?

In OECD countries, the average class size at the lower secondary level is 23 students, but there are significant differences between countries, ranging from over 32 in Japan and Korea to 19 or below in Estonia, Iceland, Luxembourg, Slovenia and the United Kingdom. Class size, together with students’ instruction time, teachers’ teaching time and teachers’ salaries, is one of the key variables that policy makers can 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. Reducing class size is not, on its own, a sufficient policy lever to improve the performance of education systems, and is a less efficient measure than increasing the quality of teaching.