A while ago, my daughter’s school explained to parents that they were reorganising literacy classes, moving to mixed-ability groups. My wife asked a simple question: “What is the evidence behind the decision to change?” The result was blank incomprehension. Evidence?

Only a couple of generations ago, most doctors had a similar attitude to evidence-based practice. Fancy statistical procedures were thought to be no match for experience, especially since every case was unique. Randomised trials were all very well in theory, but unethical in practice. That scepticism has now been completely transformed in medicine: evidence trumps seniority, while individual judgment is bolstered by online libraries full of careful analysis.

Teachers have allowed themselves to be left behind in the evidence revolution. I sympathise with the profession which is constantly second-guessed by parents and school inspectors. Teachers have grown used to fad after fad being hurled at them from the Department for Education.