There has been a vigorous debate about class sizes in schools. On one side of the debate are the enthusiasts who feel very strongly that smaller classes lead to better teaching and more effective learning. Achilles and Finn (2000: 316) have expressed this point very forcefully: 'Class size [reductions] should not just be a cornerstone, but the foundation of educational policy for… early education'. This belief has informed policy in many parts of the world; in the USA, for example, there has been huge investment in class size reductions. On the other side of the debate are the sceptics who argue that the evidence for the efficacy of class size reductions is in doubt and that there are likely to be other more cost-effective strategies for improving educational standards. This book describes a large-scale research project which set out to seek answers to the class size debate. This is not a book which seeks to either proselytize or debunk – rather it seeks to provide a sustained inquiry into the issue, based on a longitudinal study of children's progress over three years after entry into English primary schools. We hope that the book will show the value of research evidence as a main tool in this debate. It is not, though, intended to be exclusively a research report intended for other researchers. Deliberately it is written to be read by all who are interested in this topic: teachers, policy makers in local authorities and government, school governors and parents.
My interest in the class size issue began when Peter Mortimore and I were asked by the National Commission on Education to write a briefing document for them on the educational effects of class size differences (Mortimore and Blatchford 1993). Several things became apparent during our work. In looking at the current facts and figures about class sizes it was clear that there was a problem of large classes at primary level. I do not intend to describe the statistics in detail here (see Blatchford et al. 1998), but it was clear that class sizes were larger on average in primary than in secondary schools. As an example, in 1996 the average class size in England at primary was 27.5 and at secondary level 21.9. This seemed to us to turn on its head what was more sensible educationally – that is, younger children need more support from