This article was first published on the website of the Danish Center for Social Science Research (VIVE), in Danish on 5 February 2019.
It is a well-known argument in school debates that students would get more out of teaching and do better academically if classes were smaller. However, a systematic review from VIVE Campbell shows that the number of students in a class has little to do with academic results.
Intuitively, it makes sense: fewer children in a class means better conditions for learning for the individual child. Many parents prefer to send their children to schools with small class sizes, and many teachers probably also think that the framework for teaching is better if there are not too many children in the class.
A systematic review from VIVE has analysed the international research evidence on class sizes, and the results show that intuition is not always the best guide. Based on 127 studies from 41 countries, the researchers conclude that class size has at best a very small effect on students’ academic performance.
Included studies
The 127 included studies span a period of 30 years. They look at classes at the pre-school and primary school level, and measure students’ skills in reading and maths in smaller classes compared to larger classes.
Overall, the review shows that students in small classes read a little better than students in classes with more children. The difference is small, but still statistically significant. In maths, on the other hand, there is a very small negative effect, where the students in the smaller classes perform academically a little worse than students in larger classes. The effect is not statistically significant, but it cannot be ruled out that small classes may affect some students’ academic ability in the wrong direction.
An American debate
One of the major studies that the survey draws on is the ‘STAR experiment’, which was conducted in the US state of Tennessee in the 1980s. STAR stands for Student Teacher Achievement Ratio, and the results of the experiment subsequently inspired several US states to reduce the class quotient in the youngest classes. This Danish systematic review has therefore generated a lot of interest among American school researchers, says senior researcher Trine Filges, who is the lead author of the review.
“The results of the STAR experiment were once interpreted by some as proving once and for all that smaller classes were a good idea, while others felt that the effect was too small, given that it is quite expensive to reduce class sizes. That debate is still going on in the USA, and seen in that light, our results are of course interesting to both camps in the debate,” said Trine Filges.
She herself does not have a position in the debate about class sizes one way or the other, noting only that “Moving to smaller school classes has major financial consequences, including for example, that you would have to hire more teachers to teach the classes. And our analysis indicates that you cannot expect correspondingly large positive effects on the students’ academic ability.”
Click here for a plain language summary of the review.