TOO many 14 to 16-year-olds in pupil referral units and other alternative education centres are badly taught, inspectors have warned.
Yet many struggling and disaffected teenagers are turned off by mainstream schools and 10,000 are not in education at all.
The Office for Standards in Education reported this week that schools' work with key stage 4 pupils had improved as more job-related courses were introduced.
But it is concerned about low-achieving pupils, particularly those in alternative education units which frequently offered a "second-class education".
Pupil referral units are at the heart of the Government's drive to improve behaviour, but inspectors found that a fifth of teaching and a quarter of management in the units was unsatisfactory.
Other alternative centres, run by the private sector or further education colleges, were even worse. Inspectors found they were often unregistered and unmonitored. They also reported that 30 per cent of the teaching was unsatisfactory in these centres and good management was rare.
"The approach used sometimes gave a very strong impression of a concern merely to 'keep them occupied' so that activities without any educational or even social objectives, such as trips to ice rinks and bowling alleys, became a substitute for a worthwhile programme," the report stated.
Inspectors found that mainstream schools were raising GCSE results and cutting permanent exclusions by abandoning the national curriculum for vocational courses.
One in six secondaries regularly disapplied pupils from parts of the curriculum and two-thirds of teenagers in these schools exceeded expectations. But, while lessons for the disaffected and low-achievers had improved, many programmes aimed at them were still boring and lacking in purpose.
A third of schools said their work had been affected by recruitment problems and funding constraints.
David Bell, the chief inspector, said he was concerned by Government figures which showed that 10,000 pupils disappeared from school rolls between the ages of 14 and 15.
He warned it was impossible to find the real figure for "missing" pupils because tracking systems were insufficient and many alternative providers were unregistered.
"These young people are not getting the qualifications, let alone the social and life skills they need," he said.
Mr Bell added that a clearer system of vocational tests was needed to replace the "alphabet soup" of qualifications that existed.
Ofsted also recommended the introduction of national guidelines for alternative education programmes and better tracking and information exchange on pupils who left schools.
"Key stage 4: towards a flexible curriculum" is at www.ofsted.gov.uk