Schools are spending up to a year drilling their pupils for key stage 3 tests, teachers have revealed.
Saturday morning, lunchtime and after-school booster sessions for borderline pupils have also become common to ensure pupils hit the Government's target level.
Teachers say the tests have become the overwhelming focus of Year 9. Kevin Morris, a curriculum co-ordinator who visits London schools regularly, said: "Most schools seem to be doing two to three mock tests per child before the real thing. Year 9 is totally dominated by test preparation."
At Kingsbury high in Brent, north-west London, the KS3 strategy begins with a literacy summer school before Year 7, and continues with spelling and reading clubs and mentoring in Years 8 and 9. Booster classes in English, maths and science are also offered to about 80 of the school's 300 Year 9 pupils.
Christine Harvey, the school's KS3 strategy manager, said their results had risen from 74 per cent of pupils reaching the Government target of level 5 last year to 93 per cent this year.
She was seconded to the local authority to spread good practice and says many other schools adopted a similar approach. Parents are persuaded the extra work can improve children's performance later at GCSE.
Ms Harvey said the teachers volunteered to take the Saturday lessons. They were paid a small sum - "enough for a night in the pub" - funded by a Department for Education and Skills grant.
Ministers have set aside pound;39 million for this financial year to help schools improve KS3 results - the equivalent of pound;10,500 for every secondary school.
Ms Harvey said the sessions motivated pupils, who responded well to the extra attention and a system of small rewards, such as sweets, for good work. She said: "Some of them learn much more and staff and students feel much more alert on Saturdays, when they don't have as many lessons as a normal school day."
But other schools had found it hard to bring in pupils at weekends, and took them out of some normal lessons instead.
The Qualifications and Curriculum Authority has warned primaries about over-preparation for KS2 tests, but the issue has received less attention at KS3.
A teacher at a west Berkshire comprehensive, who asked not to be named, told a conference on the future of English that the drilling could be demotivating. She said pupils had been enthusiastic about Macbeth at the start of the year, but by the end "loathed it" because test preparation focused relentlessly on close analysis of two scenes.
"My head of department can say we are doing everything we possibly can to ensure pupils get the best possible results. But there are wider issues about the commodification of the education system which also need to be looked at," she said. All English teachers at her school get a detailed plan from the department head of the test preparation necessary for each half-term.
The QCA said it did not advise schools to repeatedly drill pupils with past papers. A spokesman said evidence suggested over-preparation was not a major problem at KS3 except at some schools that tried to prepare pupils with stock phrases for the writing test.