In his article “Leave schools alone to judge the best in show” (Comment, 20 September), Gabriel H Sahlgren plays fast and loose with the facts. He must know there is no evidence that linking teachers’ pay to performance has any effect on the quality of their teaching: where people carry out repetitive tasks, it is true that financial incentives can change their behaviour, but when they carry out complex activities, such as teaching, performance-related pay has, at best, a neutral and, at worst, a detrimental impact on results.

He must also be aware that devolving pay decisions to an organisational level has only one effect: to increase leaders’ pay. This has happened in independent, state-funded academies, where the average salary for school leaders has risen since 2010 while the average pay for classroom teachers has fallen.

In arguing for “stronger experimentation” in education, Mr Sahlgren reveals why performance-related pay should be kept out of schools. Improving education is not like designing a new washing machine: if it doesn’t quite work, you can’t go back to the drawing board. If this “stronger experimentation” fails, the lives of thousands of our children will be blighted forever. Should anyone be willing to take that gamble?

Martin Freedman, Director of economic strategy and negotiation, Association of Teachers and Lecturers.