This debate over class size raises some important questions. For instance what is the impact of class size on the educational outcomes of Australian children? How do class size reductions compare with other educational reforms in terms of their cost effectiveness? It turns out we know very little about how class size influences student learning in Australia so in this post I’ll take a look at what some of the better research from the US has to say about the effectiveness of reductions in class size.
The main challenge faced by researchers in trying to figure out whether small class sizes have a positive impact on educational outcomes is that the children we observe in small classes may not be representative of all children. Recent work by Louise Watson and Chris Ryan suggest that the student-teacher ratio (which as it turns out is a different thing to class size) in Independent schools have fallen relative to Government schools over the last 20 years in Australia. They also show how the socio-economic status of Government school students has declined over this period relative to children in Independent schools. If it is the case that those children enrolled at well funded Independent schools have parents with greater means and/or a greater willingness to invest in the education of their children inside the home, we may find these children to have better educational outcomes for reasons that have nothing to do with class size. The same might be true if the higher socio-economic status of a child’s classmates conferred upon them some positive peer-effect in their learning or if Independent schools had other characteristics (higher quality teachers, better facilities) that improved child outcomes independent of class size.
This isn’t necessarily a problem if educational researchers had data on all of these influences and were able to use statistical methods to control for them. The trouble is this usually isn’t the case. The only way we can untangle the causal effect of class size is to rely on policy experiments such as those conducted in the US. To date no such experimental evidence exists for Australia. Continue reading