• On average, there are just over 21 students per class at primary levels in the OECD area, but this varies from 32 per class in Korea to half that number in Luxembourg.
• The number of students per class increases by an average of nearly three students between primary and lower -secondary education.
• The student-to-teacher ratio in lower and upper secondary education is lower in private than in public institutions.

Significance

This indicator examines the number of students per class at the primary and lower secondary levels, and the ratio of students to teachers at all levels. Class size is a hotly debated topic in many OECD countries. While smaller classes are often perceived as enabling a higher quality of education, evidence on the impact of class size on student performance is mixed.

Findings

At the primary level, the average class size in OECD countries is slightly more than 21 students per class, ranging from 32 students per class in Korea to fewer than 20 in Austria, Denmark, Greece, Iceland, Italy, Luxembourg, Mexico, Portugal, the Slovak Republic and Switzerland.

In lower secondary education, the average class size is 24 students, ranging from 36 students per class in Korea to 20 or fewer in Denmark, Iceland, Ireland (public institutions), Luxembourg and Switzerland.

At the primary level, the ratio of students to teaching staff, expressed in full-time equivalents, ranges from 26 students or more per teacher in Korea, Mexico and Turkey to fewer than 11 in Greece, Hungary, Italy, Norway and Portugal. The OECD average in primary education is 16 students per teacher, and 13 students per teacher at secondary level (see Chart D2.3 in -Education at a Glance 2008).

Across the OECD, average class sizes at the primary and lower secondary levels do not differ by more than 1 to 2 students per class between public and private institutions. However, there are differences between countries. For example, in Poland, Turkey, the United Kingdom and the United States, the average class size in public primary schools is notably higher - four students or more per class - than in private schools. It should be noted, however, that the private sector accounts for at most 5% of primary students in these countries. At lower secondary level, where private education is more prevalent, differences in class size tend to be smaller than at the primary level.

Trends

Among countries with comparable data, class size tended to decrease between 2000 and 2006 among those countries that had larger class sizes in 2000, such as Japan, Korea and Turkey, while it increased or remained the same in countries that had the smallest class sizes in 2000, such as Iceland. However, overall there was little substantial change in class sizes.

Definitions

Data refer to the 2005-06 school year, and are based on the UOE data collection on education statistics administered by the OECD in 2007. Class sizes have been calculated by dividing the number of students enrolled by the number of classes. The ratio of -students to teachers has been calculated by dividing the number of full-time students at a given level of education by the number of full-time teachers at that level.

Further reading from OECD

Improving School Leadership (Vol. 1: Policy and Practice) (2008).

21st Century Learning Environments (2006).