The Impact of rising class sizes

Is this really a problem? The debate about class sizes has been going on for a long time with the argument that larger class sizes equates to a poorer performance by students and hence to a drop in grades. The Labour party pledged in 2015 that class sizes for infant classes would be capped at no more than thirty pupils.

Around the same time as this pledge to reduce class sizes, the head of the OECD PISA surveys commented on the myth that small class sizes raise standards. His argument was that in some Asian countries class sizes are larger, but it is the quality of the teaching which is the focus.

The Sutton Trust’s research suggests the following as having the most impact on improving attainment:

  • teachers’ subject knowledge, including their ability to understand how students think about a subject and identify common misconceptions
  • quality of instruction, which includes using strategies like effective questioning and the use of assessment

Pointing to what other countries do and their approach to education tries to find a simple ‘cause and effect’ link between those countries in Asia such as Hong Kong, where the attitudes and values towards education are high as well as the level of private tutoring. In South Korea, a recent television food documentary programme I saw, visited a school because of the interest in school meals, but it was fascinating to hear the conversation turn to Korean education in which pupils in larger class sizes spent all day in school and then worked on study and extra tuition classes up to 2am in the morning!

What we need is to see some evidence that there is a relationship between class size, pupil performance and the level of results. How can PISA results which compare performance across countries through the PISA test at the end of year 11 also show the cultural and social conditions between countries in which some children are working by the age of ten years, and for whom internet access, never mind computer resources, are non-existent?

There has been large scale research and meta-analysis about the factors that influence educational attainment, Professor Hattie being one well-published and influential author in this matter. In one of his studies there is a long list of items measured to try to find how each one correlates to the impact on attainment.

An extract from this chart suggests a low correlation of class size to impact on attainment with a 0.21 correlation.

Image displaying correlation of low class sizes to impact on attainment

The thing to remember is that such studies have wide-ranging parameters including the ages of pupils, school locations and socio-economic factors to name a few.

However, a little digging around does uncover two longer-term research studies around the effects of class sizes that have sought to specifically address this question. One study was STAR, begun in 1985 by the University of Tennessee, the other by Peter Blatchford et al from University College London. In the STAR study there were three parts and the conclusions were that class size mattered, especially for the younger-age pupil and for lower attaining pupils.

It was also from this research that the myth of a class size of 20 or lower was needed to improve attainment, but I digress. A quote from the STAR Project research explains:

“Observations…confirmed that the children…originally enrolled in smaller classes continued to perform better than their grade-mates (whose school experience had begun in larger classes) when they were returned to regular-sized classes in later grades. Under the third phase, Project Challenge, the 17 economically poorest school Districts were given small classes in kindergarten, first, second, and third grades. These districts improved their end-of-year standing in rank among the 139 districts from well below average to above average in reading and mathematics.”  The Future of Children . CRITICAL ISSUES FOR CHILDREN AND YOUTHS. Vol.  5 No.2 – Summer/Fall 1995.

The study by Blatchford, P., Bassett, P., Goldstein, H., and Martin.  C.  (2003) “Are class size differences related to pupils’ educational progress and classroom processes?” and the “IoE CSPAR Study” of more than 20,000 pupils found that class size did in fact have an effect with a relationship between the size of the class and the education progress related to literacy and maths.

So do class sizes matter? From research it suggests that class size related to progress does make a positive difference. However, in trying to answer such as question, what is clear is that it is not such a simplistic cut-and-dried answer as it appears on the surface.

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