Do small class sizes improve student achievement in primary and secondary schools?
Increasing class size is one of the key variables that policymakers can use to control spending on education. I’ve tried my best to summarise this 110-page research document for the busy classroom teacher and school leader.
A modest return…
This systematic review examines the impact of class size on academic achievement. The review summarises findings from 148 reports from 41 countries. Ten studies were included in the meta-analysis. A total of 127 studies, consisting of 148 papers, met the inclusion criteria. These 127 studies analysed 55 different populations from 41 different countries and included pupils from nursery up to further education age.
The consensus among many in education research is that smaller classes are effective in improving student achievement which has led to a policy of class size reductions in a number of US states, the UK, and the Netherlands. This policy is disputed by those who argue that the effects of class size reduction are only modest and that there are other more cost-effective strategies for improving educational standards.
The effectiveness of small class sizes for improving student achievement has been one of the most debated issues in educational research. One strand of class size research points to small and insignificant effects, another points to positive and significant effects. In this review, the intervention has been class size reduction. Studies only considering average class size measured a student-teacher ratio at school level (or higher levels) were not included.
This research suggests evidence that there is an effect on reading achievement, although the effect is very small. We found a statistically significant positive effect of reducing the class size on reading. The effect on mathematics achievement was negative and not statistically significant.
Class size reduction is costly and the available evidence points to no or only very small effect sizes of small classes in comparison to larger classes. Taking the individual variation in effects into consideration, we cannot rule out the possibility that small classes may be counterproductive for some students. It is therefore crucial to know more about the relationship between class size and achievement and how it influences what teachers and students do in the classroom in order to determine where money is best allocated.
- Overall, the evidence suggests at best a small effect on reading achievement.
- There is a negative but statistically insignificant effect on mathematics.
- Class size reduction is costly.
- The available evidence points to no or only very small effect sizes of small classes in comparison to larger classes.
- We should not rule out the possibility that small classes may be counterproductive for some students.
It is therefore crucial to know more about the relationship between class size and achievement in order to determine where money is best allocated. The research is published by the Campbell Collaboration, Norway (2018). You can download the full paper here.
There is a wealth of academic papers available here – search field terms include “2010+ and U.K.”. With a bit of investigative work, you may be able to refine this by subject and/or demographics.