This week’s GCSE results have brought much good news. Students in England, Wales and Northern Ireland have taken a record number of examinations, 5,711,558, and achieved the best pass rate so far, 53.6 per cent, among the top three grades. Entries for the three core subjects of maths, English and science have remained solid.

Elsewhere, however, there are some potentially worrying developments. The average number of GCSEs per pupil appears to have dropped, for example; the School Curriculum and Assessment Authority has promised to investigate the causes. There has been speculation that schools, keen to compete in league tables, are ignoring weaker candidates who have then ended up sitting fewer exams.

There has also been a notable 30 per cent fall in the number of candidates taking technology. This is associated with an even more dramatic increase in the numbers taking home economics (77.7 per cent) and greater numbers sitting business studies, computing, music and art and design.

The examination boards and SCAA attribute the fall in technology entries to the fact that it has been, temporarily, an optional subject - it will become compulsory once more this autumn.

But according to the National Association of Head Teachers, this is a further sign that schools are ill-equipped and inadequately staffed to teach technology to 15 and 16-year-olds. Given a choice in the matter, he says, they have deserted the subject in large numbers.

“Secondary schools are not in a position to deliver key stage 4 technology and it’s time something was done about it,” said the association’s general secretary, David Hart.

“Technology colleges are all very well, but that doesn’t help the majority of schools. It’s a really serious issue. Technology is crucial. The NAHT would make it the fourth core subject, if there were such a thing.”

Earlier this year, a study by Professor Alan Smithers at the Centre for Education and Employment Research at Brunel University found technology departments so badly funded that they scavenged some materials from industrial skips and dustbins.

Although a new record, the total number of entries has been causing particular concern. It has increased by 1.1 per cent since last year, but a corresponding rise in the total number of 16-year-olds is much greater - 3.1 per cent. The average number of exams per pupil has actually dropped.

There are several possible explanations, the most worrying of which is that schools are attempting to “fix” league table results by refusing to enter weak candidates.

This would, however, be a mistaken policy as the Government’s performance tables take as their basis not the number of pupils entered, but the total number of 16-year-olds registered with the school - even if they have left at Easter. Failing to enter pupils cannot improve the average grade.

There are other explanations. One is the cost of entering a GCSE - around Pounds 30 a shot. Schools may be less willing to enter doubtful candidates - possibly with the best interests of the pupil in mind.

“Schools will be careful about the way they spend their limited resources, ” said a spokeswoman for the National Union of Teachers. “They will be reluctant to enter kids who they believe have little chance of success - thereby freeing money to help the pupils in other ways. It may be a considered decision against a background of limited resources.”

The figures are complicated by changes in the rules governing the national curriculum, said Heather James, assistant chief executive with the Northern Examination and Assessment Board. Last year schools entered unusually large numbers of candidates in technology and double humanities (geography and history), mistakenly believing that the subjects were compulsory.

This year, they were very definitely optional, and both technology and history showed notable drops in popularity.

The statistics are also obscured because many of the candidates are mature students, not registered at school. The Government only has figures for the total of 16-year-olds. Neither the total number of candidates nor their origin is available.

The suspicion nonetheless remains that schools are devoting an undue level of attention to candidates capable of achieving grades A-C. “The league tables have encouraged schools to target pupils who may, with additional effort, get a C,” said John Dunford, president of the Secondary Heads Association. The way to prevent this, he suggests, is to list schools according to the average scores per child - across the whole range.

A Government spokesman rejected the idea that schools concentrate on grades A-C, pointing out that the pass rate for grades A-G has continued to rise.

* The number of subject entries in Wales fell by 0.3 per cent this year. Like its counterparts in England, the Welsh Joint Education Committee attributes the fall to the lack of technology entries (technology was not compulsory this year). The overall pass rate in grades A*-G fell by 0.1 per cent; the percentage of candidates reaching grades A*-C rose by 1.4 per cent to 54. 1 per cent.