There is little evidence to suggest we can link the performance of a teacher to a set or sets of exam results.

There is, however, plenty of evidence to suggest hereditary and environmental factors have the dominant impact. This evidence seems to be conveniently ignored. In a recent and extensive study by researchers at Kings College in London, they concluded that individual differences in educational achievement at the end of compulsory education are not primarily an index of the quality of teachers or schools: much more of the variance of GCSE scores can be attributed to genetics than to school or family environment.

In a national twin sample of 11,117 16-year-olds, they found that heritability was substantial for overall GCSE performance for compulsory core subjects (58 per cent) as well as for each of them individually: English (52 per cent), mathematics (55 per cent) and science (58 per cent).

'Teacher factor'

In contrast, the researchers also found that the overall effects of shared environment, which includes all family and school influences shared by members of twin pairs growing up in the same family and attending the same school, accounts for about 36 per cent of the variance of mean GCSE scores. These significant findings surprised even the researchers themselves.

Seminal research by the American Statistical Association (2014) concluded that only 1-14 per cent of educational outcomes can be attributed to the "teacher factor" and within that, there are plenty more factors outside of the individual teacher's control to take into account, such as class size, available teaching resources and budgets. The Coleman study on educational equality concluded that the remaining 86 per cent can be put down to "out of school" factors.

This explains the findings from Cambridge Assessment last year that summarised that: "It’s normal for schools’ results to change – even when teaching practices stay the same.” Yes – this is because, for the most part, results will vary depending on the children and parents, rather than the teachers.

The argument running counter to this usually centres on individual cases of schools – some in deprived areas – that achieve outstanding results.

Uncomfortable reality

Of course, there are schools that are well-led and where teaching and learning is excellent. They are maximising their impact within the 14 per cent. But to say their impact goes further than that would run against the evidence.

The narrative around "outstanding" schools is often built around an undisputed certainty that it's they who "turned around the school", that it's the way the leadership team led the school that's secured its status and that collective teaching is simply better there. But evidence suggests that is just not the case, however difficult that is for some humans to accept when our natural desire is for recognition and meaning.

The uncomfortable reality is that thousands of "requires improvement" schools are doing exactly the same things as their "outstanding" counterparts. I'd bet my bottom dollar that if you switched ten whole staffs from 20 outstanding schools with those from required improvement schools for 5 years, only 1-14 per cent of them would experience a significant change in results, on both sides of the exchange.

So in short, the success of an education professional cannot be gauged using the metrics of progress and attainment of their students.

Direct correlation

In light of this, it's also worth pointing out that numbers of pupil premium students in a school should be seen alongside the cultural and social traditions of the collective student body. A group of economically disadvantaged students could be culturally advantaged by a strong commitment to education from parents and community. White working-class boys perform the worst in schools and this isn't just about money.

This body of research is clear – the "teacher factor" is nowhere near as significant in educational attainment as is sometimes painted by politicians and educationalists. It can't be used to judge the "success" of a teacher or school leader.

In Ofsted, we have an organisation that grades schools based on their "outcomes", taking very little account of the fact teachers have little control over them. A recent report by education data lab showed there is a direct correlation between the Progress 8 results of a school and the Ofsted gradings they received. Of the 735 schools who were inspected between September 2016 and August 2017, only 3 per cent of schools with low Progress 8 scores got a "good" or "outstanding" rating from Ofsted.

So, in other words, the better the genes, family life and location of your students, the better Ofsted grade you get.

This is borne out by other statistics, which show that Grammar schools, who obviously take students from higher starting points academically, get better Ofsted grades.

Putting aside the issues over the reliability and consistency of Ofsted grades, the underlying travesty is what the inspectorate is basing its judgements on, more than how they are going about it. We need to try and move the debate on from the way in which Ofsted carry out individual inspections to the way in which the inspection framework is used – with "outcomes" trumping everything else as a general rule. It's not right.

Something to shout about

Ofsted grades tell us very little about the effectiveness of staff within a particular school. An Ofsted grade will never be able to quantify the impact of a fleeting or longer-term relationship that inspires a student to "be" more in life. These relationships are not only built inside the classroom but within a wider school context, showing how nuanced such things are. This inspiration may have zero impact on academic attainment but will carry an invisible benefit – something that can’t be “evidenced”.

There is a difference between learning and an exam. That being, an exam is a one-off, high-stakes performance measure. We are placing a hell of a lot of faith in the formulation and breadth of exams, the people who compose them and their relative assessment objectives. The constant changes to the content and structure of exams in recent years, from Sats to GCSEs, renders the actual validity of those exams as a measuring tool uncertain, never mind my arguments here which presume they are.

Despite all this, the lure of being hailed as “outstanding” may be too much to pass up – plastering accolades over the front of the school, on bus shelters or over social media is too tempting. Just yesterday I encountered a school that flashes up the outstanding badge on their website and insists you click on it before you can access the rest of it. By shouting about how great and reasonable Ofsted inspectors were in delivering their positive verdict, we reinforce the entire system, and the lie it's based upon.

Can't we just shout about the children in our school, who they are, the talents they have? I'm hoping if you've read this far, you might reconsider your own schools' media policy.

Thomas Rogers is a teacher who runs rogershistory.com and tweets @RogersHistory

For more columns by Tom, view his back catalogue

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