An all-boys school has boosted its maths GCSE results by knocking down a wall between classrooms and teaching two classes as one.

John Atkins, the head teacher of Kemnal Technology College, Sidcup, southeast London, has found that class sizes of up to 75 pupils produce higher grades, contrary to the prevailing belief that small class sizes produce better academic results, Mr Atkins, who introduced double-class teaching four years ago in response to a shortage of maths teachers, is so pleased with the results that he has converted a second classroom to accommodate supersize classes.

“A maths teacher left, so over the weekend I converted a room into a double classroom to take two classes at the same time,” he said. “I got in an excellent maths teacher, with three teaching assistants, and wired up two interactive whiteboards. It was a risk, but it proved to be very successful and we have the exam results to prove it.”

The first group of Year 9 pupils taught in this way all achieved far higher grades than had been predicted for them when they were taught in smaller classes of 25 to 30. The next group of 75 Year 11 pupils also exceeded expectations. A half of pupils went on to achieve A* to C grades at GCSE after the double-class teaching, compared with predictions of just 22 per cent.

Teacher-pupil ratios and class sizes have been a subject of controversy for years. The prevailing wisdom is that smaller classes lead to better pupil motivation and behaviour and higher attainment. Independent schools have pushed this line for years.

Average class sizes in private schools in Britain at primary and secondary levels are just above ten, compared with 23.6 and 24.9 in primary and secondary state school classes respectively.

Gordon Brown used his Budget in March to highlight this differential and promised to close the funding gap between state and private schools, with the comment: “We know the educational benefits of more individual attention, small-group teaching and tutoring, and that they are easier to get where the overall teacher-pupil ratio is low.”

Mr Atkins said that his experience was quite different at Kemnal Technology College, an academy sponsored by Lord Harris of Peckham.

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