Does class size matter?
The debate about the impact of class size on results is one of the most contentious in education policy. The unions argue for smaller classes, the economists for more efficient use of resources. What does the data say?
The chart shows the relationship between pupils per teacher and average results on national tests. The relationship exists — but it is weaker than most people think.
Schools with extremely high pupil density (above 16–17 pupils per teacher) tend to have lower national test results. But below that level, the relationship is almost non-existent. A school with 10 pupils per teacher does not perform noticeably better than one with 13.
This is likely because teacher quality, pedagogical method and the home environment play a larger role than whether there are 22 or 28 children in the classroom. International research (the STAR study in Tennessee, Hattie 2008) confirms the picture: class size has an effect, but it is smaller than we intuitively believe.
Statistics: academic year 2023/24. Source: Skolverket open data, Kolada and SCB. Processed by Skolkoll. Glossary · About the data.