Peter Blatchford
The class size debate has opened up once again. The prevalent view this time seems to be that class size is unimportant. This was apparent in the media coverage of one London council leader who wanted the cap of 30 in a class for the youngest pupils to be relaxed. The thinking is that reducing class sizes is not a cost effective use of public funds and that money could be better spent, particularly on improving teaching quality.
More worryingly, more and more people are now arguing that class sizes could even rise. The judgment of teachers themselves – which we have found is overwhelmingly that teaching and learning are better in smaller classes – often gets overlooked or even denigrated as self serving.
For me, much of the commentary on this topic contains a common but flawed way of thinking about class size. No one could disagree that teachers and teaching quality are the most important ingredient in successful education. But the two biggest studies of class size effects – the STAR project from Tennessee and our own study based at the IOE – are also clear: the number of pupils in the class significantly affects young pupils’ educational progress. The mistake I think is to assume a choice has to be made, as if teaching and class size are mutually exclusive. The number of pupils in a class is an important contextual influence on the quality of teaching which takes place, and the important thing is the way that class size and teaching interconnect.
The question I think needs to get asked more is what teaching approaches work best in smaller (or larger) classes? This is a particularly pressing question in a number of countries in Asia. In Hong Kong for example, despite high performance in international comparisons of academic success, they are reducing class sizes as a matter of policy. In our extensive series of observation studies of class size effects, as part of the IOE research, we found that in smaller classes there was more individual attention and more pupil classroom engagement. But other research has also found that teachers do not always alter their style of teaching when faced with fewer pupils in the class, and could therefore benefit from help with effective strategies in small classes.
During recent visits to primary schools for a current research project on the educational supports given to pupils with special educational needs (SEN) in mainstream classes, I have been struck by one way that class size and teaching are intimately related. It is clear that teachers face an extremely difficult task when seeking to teach pupils in often large and very varied classes that sometimes include pupils with special educational needs.  
Those who argue that class size effects are unimportant seem fixated on evidence exclusively couched in terms of academic achievement test scores. But there are other features, including skills at differentiating the curriculum for pupils at very different levels, which are affected by class size but rarely get a mention, and still less studied in research.
So pitching class size against teaching is far too simplistic. They are both important. A key task for the future is to develop and evaluate effective teaching approaches when faced with different numbers of pupils in the class.