Study after study has shown that, on average, educational achievement is linked to factors which are external to schools. Here are a few:
Research and Information on State Education (RISE), an independent charity which produces and publicises research and information about state education published How intake and other external factors affect school performance (Will Cook 2013).
The Royal Society of Arts (RSA)’s The social class gap for educational achievement: a review of the literature (Emma Perry and Becky Francis, 2010)
Education: New Labour’s Top Priority from Towards a More Equal Society?: Poverty, Inequality and Policy Since 1997 (Ruth Lupton, Natalie Heath and Emma Salter, 2009)
An Anatomy of Economic Inequality in the UK, Report of the National Equality Panel (John Hills, et al 2010)
These results have been consistent over time.
This graph by Christopher Cook shows the average picture of exam results in England by wealth, for example:
Many education commentators hold the following broad areas responsible for disadvantaged children achieving lower academic results on average than their more affluent counterparts:
Low Expectations of the Disadvantaged by the school system
Behaviour Issues in Schools
Assessment Issues in Schools
My view is that, where an education commentator makes the assumption that the relative achievement of pupils - and by extension schools with a significant proportion of advantaged or disadvantaged pupils – is primarily due to any or all of these broad areas, it should be remembered that ‘Social class remains the strongest predictor of educational achievement in the UK’ (p1, Perry and Francis, 2009), and that, clearly, social class is influenced by factors external to a school.
Where an education commentator makes the assumption that schools - and by extension teachers – have the biggest impact on the academic achievement of children in their charge, any case, policy or commentary built on this assumption is fundamentally flawed.