"The great majority of teachers have no formal qualification in information technology nor relevant commercial experience", says the Office for Standards in Education in a new analysis of the secondary curriculum.
Twenty per cent of teachers say they have only taken a brief IT awareness course, according to the report based on inspections in 1997-98.
It pinpoints a wide and growing gap between schools which meet curriculum requirements and those which do not.
Teaching overall was "largely unsatisfactory" in the 53 per cent of schools which did not comply with IT usually the worst taught subject at both key stages.
Pupils at nearly three out of 10 schools were making unsatisfactory progress in the subject at key stage 3, while the figure for KS4 was 38 per cent.
The report, on all the national curriculum subjects and religious education, also says that work in many schools in art and design and technology was being constrained by lack of resources.
Some 18 per cent of schools -particularly boys' grammars - failed to comply with the legal requirement for all pupils to take design and technology at age 14, it adds.
The report identifies a rapid improvement in standards in KS3 English, where 65 per cent of pupils achieved level 5, as against 56 per cent in 1997. The progress is put down to greater attention being given to pupils' literacy skills when they transfer from primary schools.
But in mathematics, it points out that stronger pupils are pulling away from the less able throughout key stages 3 and 4. It asks schools to take action to improve the progress of the lower achievers.
The day-to-day assessment of pupils could be better in all subjects and such information used to improve future lesson plans, the report says.
Copies of the report are available free from PO Box 6927, London E3 3NZ, tel. 0171 510 0180.