Harry de Quetteville cited Sutton Trust teaching research in his Telegraph defence of testing

Some parents are very worried that Sats test are putting too much pressure on their children. But what if the tests were not primarily about measuring the performance of children – but of their teachers? The Sutton Trust reckons that “gains in pupil test scores are the best available metric to measure teacher performance”.

And why are good teachers important? The Sutton Trust has the answer again. “The difference between a very effective teacher and a poorly performing teacher is large. For example during one year with a very effective maths teacher, pupils gain 40% more in their learning than they would with a poorly performing maths teacher.”

Moreover, if you care about social mobility (which you should, particularly if you claim to care about education) then the value of good teachers is greater still. “The effects of high-quality teaching are especially significant for pupils from disadvantaged backgrounds: over a school year, these pupils gain 1.5 years’ worth of learning with very effective teachers, compared with 0.5 years with poorly performing teachers. In other words, for poor pupils the difference between a good teacher and a bad teacher is a whole year’s learning.”

Read his full column here