This note presents the findings of the most methodologically robust research, which assesses the impact of reducing class sizes on pupils’ academic performance and their long-term prospects. Contrary to a long-held belief, these effects are significant when compared with other large-scale, rigorously evaluated education policies. The absolute cost of doubling the number of Year 1 and Year 2 classes justifies targeting this policy at the most disadvantaged pupils, but the investment pays off as soon as there are net effects on the beneficiaries’ employment prospects of as little as 1 per cent. However, many uncertainties remain, particularly regarding the relationship between smaller class sizes and teaching practices.
Does class size affect academic achievement?
This paper examines the link between class size and academic performance, using strategies that effectively reduce selection bias.
Reference IPP Policy Brief No. 28
Presentation
Key Results
- A number of international research studies, most of them recent, assess the effects of reducing class sizes on pupils’ progress by convincingly controlling for selection bias.
- These studies show that splitting a class of 24 pupils into two groups significantly improves pupils’ average performance, and it is even possible to observe the long-term effects on their educational trajectories and professional/vocational integration into employment.
- These effects are observed even though teachers do not receive specific pedagogical support.
- The high cost of such a policy justifies targeting it at the most socially disadvantaged pupils, which is in line with the objective of reducing inequalities.
- The cost-benefit analysis indicates that such a policy is cost-effective as long as it increases the future earnings of its beneficiaries by 1 per cent, through its benefits on educational outcomes.
