Children taught by the worst teachers get at least a grade lower pass mark at GCSE than those taught by the best, research out today claims.
A study to be presented to the Royal Economic Society's annual conference reveals a pupil taught by one of the weakest teachers would be worse off by more than one grade in that subject at GCSE. This finding is based on comparing teachers among the bottom 5 per cent in the country with those among the top 5 per cent.
A pupil taught by a teacher in the bottom 25 per cent in the country would be given a grade between a third and a half (0.42) lower than one taught by a teacher in the top quartile.
"A pupil taking eight GCSEs and taught by eight 'good' teachers [from this group] will score three to four more GCSE points [grades] than the same pupil in the same school taught by eight 'poor' teachers," it concludes.
"The gain per pupil per subject is obviously greater looking at the extreme range [of teacher ability]."
The study, by Professor Simon Burgess from the University of Bristol, is the first time such research has been carried out. It is based on the GCSE exam results of more than 6,500 pupils in English, maths and science.
"Anecdotes abound of the transformational effect of excellent teaching," Professor Burgess' report says. "Yet trying to quantify this is difficult." However, the research concludes: "So teachers do matter." Meanwhile, in a separate study for the same conference, researchers conclude that boys would be better off being taught English in single-sex classes.
The research, also by Professor Burgess in collaboration with Helen Slater and Neil Davies, shows that – throughout schooling from tests for seven-year-olds to GCSEs – boys in English classes where girls predominate do worse in tests and exams. In maths and science, both sexes do better if girls are in the majority.
"The results imply that in primary schools, at least, boys would benefit greatly from being taught English in single-sex classes, which would have little effect on girls' outcomes," Professor Burgess said. By the time they leave primary school, the gender gap – particularly in reading – is pronounced, his report added.
The study: how teachers' influence was rated
*To identify the extent to which good teachers could improve a pupil's exam performance, the researchers compared the results pupils got in their GCSEs with those they got aged 14 in their national curriculum tests in English, maths and science. The comparison revealed whether they had fared better or worse than expected.
*To determine the teachers' ability, the researchers looked at the teacher's age, experience, number of years in the school, salary and spine point (a point of the teacher's salary scale which denotes how far they have progressed) and any leadership allowances they may have been awarded.