The latest figures from a thinking skills project, backed by Education Secretary David Blunkett, show for the first time that its methods are successful in highly selective schools, according to the academics who devised the project.
Previous evidence showed that CASE, the Cognitive Acceleration through Science Education project, boosts exam performance in schools with intakes of average or below average ability.
New data in the report on CASE intervention show that it has also boosted GCSE results in a girls' grammar school and a boys' independent school which used the scheme to help their 11 and 12-year-olds.
Although the new figures cover only a small sample - 11 schools - the project team believes that thinking skills boosted the GCSE scores of the brightest pupils. Pupils who have taken part in CASE scored a grade higher than expected in science GCSE, according to the latest figures. The same pupils improved their English and maths results by almost a grade, it also found.
Chatham girls grammar and St Albans school, a boys' inependent, achieved better GCSE results in English, maths and science last summer because they had used CASE, the report claims.
Michael Shayer, of King's College, London, said: "On the basis of their relatively able intake, such schools might expect that between 70 and 80 per cent of their students would achieve grades A-C at GCSE. In 1999 they achieved about 95 per cent in science and maths and nearly 100 per cent in English.
"They had used the cognitive acceleration methods in science lessons in Years 7 and 8 and it seems that the effect on students' thinking both lasted the next three years to GCSE, and also transferred from the science context to English."
CASE aims to train pupils by getting them to consider the thought processes behind science for one hour every fortnight using specially-prepared resources. But critics of the programme put its successes down to enthusiastic teaching.
"GCSE 1999, Added-Value from Schools adopting the CASE
intervention", is published by the Centre for the Advancement of Thinking, School of Education, King's College London, Waterloo Bridge Wing, Franklin-Wilkins Building, London SE1 8WA, or e-mail firstname.lastname@example.org