SCHOOLS are working together to cut the difference in exam grades between subjects.
Brighouse High and Hipperholme and Lightcliffe High are among 50 schools in England involved in a project run by the National College for School Leadership.
The organisation wants to get rid of differences between pupil performance in different subjects or teaching groups.
For the past 18 months, 25 of the schools - including Brighouse - have undertaken a research project.
They looked at how individual GCSE pupils were progressing in each subject.
If significant numbers of students who did well in most subjects were found to struggle with one, that subject would be focused on.
The 25 participating schools have now been paired up with another 25 to compare methods used to reduce the difference in levels of achievement.
Brighouse High has been paired with Hipperholme and Lightcliffe High.
Brighouse headteacher Graham Soles said: "They will benefit from us and they will have good practice we can learn from."
Achievement variations often went undetected, because each school department had different ways of measuring students' progress.
But at Brighouse High there was a ``common" database, which measured students' progress in each subject the same way.
The project has been a success. A* to C grade GCSE results have gone up by 7%.
This means 67% of the school's pupils are getting A* to C grades.
Mr Soles added: "The research project has been beneficial to the school. Variation within a school is an important issue."
Research by the Organisation for Economic Co-operation and Development shows that achievement variation within British schools is greater than in any other developed nation.
Hilary McEwan is Yorkshire and Humber co-ordinator for the NCSL's Leadership Network, a group of 250 headteachers working on education reform.
She said: "Differences in performance between departments or teachers can seriously affect overall levels of pupil attainment.
"The ultimate prize is to limit variation across the school system, so that children can perform at their highest level across subjects without unexplained dips," added Ms McEwan.