Does it make a difference how many pupils are in your class? Your answer to that will probably depend on who you are - specifically, on whether you are a teacher or an academic.

Many academics would argue that class size has little impact on pupil outcomes; this is what much of the research in this area has shown and, as such, it suggests that class size isn’t something that we really need to worry about.

Teachers, on the other hand, know that class size does matter. A lot.

According to Peter Blatchford, professor of psychology and education at the UCL Institute of Education, this conflict of views, between researchers and policymakers on the one side and classroom practitioners and school leaders on the other, has progressed very little in the past 50 years.

“There still seems to be a very enduring and often acrimonious argument about whether class size matters,” he explains.

“To put it at its most crude: on the one side of the argument, you’ve got what you might see as practitioners, and almost everything I’ve ever read and everything I’ve ever experienced in schools suggests that teachers are overwhelmingly of the view that, other things being equal, the smaller the class, the better for teaching and learning. And that’s supported by people around teachers, senior management and teacher unions and so on. 

“And then on the other side of the argument you’ve got a number of researchers and policymakers and policy-related folks, who argue that it doesn’t matter that much.” 

Blatchford refers to this difference of opinion as the “class size conundrum” in his new book, Rethinking Class Size, which has been made freely available on open access through UCL Press. In writing the book, together with his co-author, Anthony Russell, Blatchford set out to re-examine the research around class size, in the hope of finally reconciling the two completely different points of view. 

Class size: What does the research say?

So, what did he find out? The problem with much of the existing research, Blatchford says, is that it only looks at the relationship between class size and pupil attainment - usually attainment in first language and maths - and doesn’t take into account other aspects of teaching and learning that may be affected by class size. 

In larger classes, teachers have to teach in a different way than they would in a class with fewer students, and this can have all manner of implications, he says.

“For example, it could well be the case that in larger classes, teachers are much more inclined to concentrate on the basic subjects and probably more inclined, in a sense forced, into more whole-class teaching,” Blatchford explains. “We show that putting a full range of activities on can be compromised by large classes, so [there’s] less opportunity for practical and investigative activities.” 

In large classes, there tends to be less one-to-one attention and less pupil active engagement, he adds. And class size also affects aspects of classroom management, including the way that teachers set up groupings, and the amount of knowledge they have of individual pupils.

“All of this feeds into the idea that it may be in large classes that the basics don’t suffer, but other things may. So that’s kind of the trade-off really,” Blatchford says. “So, if you look at the evidence only on class size in relation to first language and maths, it may not show a great effect. But there are other things in the system that are affected by class size that we’re not really looking at.”

One crucial factor that researchers often ignore, Blatchford says, is the effect that larger classes have on teachers themselves, particularly in terms of the marking and admin load - something that can have huge implications for teacher retention.

“In the book we have cries of pain of teachers saying, ‘Look, I’ve got 35 in the class, I’ve got three bits of work to mark tonight, that’s well over 90 bits of work. Let me out!’ So there’s a lot of concern, I think, that comes out, which we try to articulate. But this isn’t helping to keep people in the profession when their cries for help are not really being heard,” he explains. 

Are smaller classes better?

As well as teachers, there are two other groups that Blatchford’s work has shown tend to be negatively affected by larger classes: younger children and pupils who have lower attainment or special educational needs.

“If you look at the OECD [Organisation for Economic Cooperation and Development] figures on class size, the UK is unique in having larger classes at primary than lower secondary. And it does seem somewhat perplexing, pedagogically, that it is that way around. Given the strongest findings, I think it’s fair to say, across all the studies, that the biggest effects are with the youngest children - the priority group would be the youngest children in school,” Blatchford says. 

But what does all of this mean for teachers? Few practitioners would be likely to disagree with Blatchford’s findings - after all, his research confirms what teachers, on the whole, already believed about class size. Yet teachers themselves have very little, if any, control over how big their classes are

Blatchford recognises this. In the book he outlines some steps that teachers can take to reduce the workload that a larger class creates, if they do find themselves struggling with things like marking.

“We try to take it further and develop ways in which you can think about teaching in large and small classes and one of the routes we take is through how one can deal with the whole business of marking. There are some recent reports that are quite helpful. There are ways in which one can try to rethink the whole way in which we do individual marking after a lesson, because it can be pretty soul-destroying for teachers when they’ve got so many to do.”

However, there is another way that Blatchford’s book might be a positive force for those working in schools. It contributes to the view that education research needs to pay more attention to the act of teaching, and how policies and initiatives affect the work that teachers have to do, rather than only looking at outcomes for pupils as the measure of whether something is worth doing.

And if more policy-makers and researchers fully understood teaching, Blatchford suggests, then we might have more initiatives focused on the needs of teachers - which ultimately would help to improve outcomes for pupils.

“My sense is that underlying the view that class size isn’t terribly important is a view that teaching is about lecturing. It’s about passing on information. And this is another thing that bothers me - that the people who do this type of research, often, because they’re not teachers, don’t appreciate, especially at primary school. That’s a very limited view of what teaching is,” Blatchford says.

You can download Rethinking Class Size by Peter Blatchford and Anthony Russell for free via UCL Press