Examiners face a challenge grading the AS papers because the exams have never been taken before. They cannot compare scripts with those of previous years to ensure consistent marking, as they did for A-level.
The final A-level award next year will be an aggregate of the AS and A2 grades. So if examiners set the grade boundaries too low for AS-level then next year's A-level results will be artificially inflated and vice versa.
Examiners face a major difficulty in establishing what should constitute A to E grades for the new qualification. Some students will do the AS with no intention of progressing to A2. These students may not be as able or take the exams as seriously. If grades come out much lower than expected, it may not be because boundaries have been set too high, but simply because some candidates are less motivated and able. Boards therefore need to know if students intend to carry on to do the full A-level before they can decide if the grade boundaries are right.
In a letter sent out this month schools and college were asked which students planned to continue on to a second year of study.
But schoos and colleges say it is impossible to supply that information until after the AS results have come out.
Jim Dobson, servicing officer with the Joint Council for General Qualifications, said that if grades issued this summer were out of line with those awarded in the past at A-level it would have a knock-on effect a year down the line. "There will be a time bomb lurking underneath next year's results if this year's AS results are not pitched at the right level because the final award is an aggregate of the AS and A2 grade. That is why we need as wide a range of evidence as possible."
Teachers' fears about AS marking have filtered down to students. Viral Barot, a sixth-former at Christ's College, East Finchley, sat English and chemistry this week. He said: "At the start of the year most of the teachers had no idea what to teach us. They were using the old A-level syllabus.
"I felt I did OK in English and the paper was fair but we don't know what it takes to get an A."
The head of English, Maggie Airey, said: "The questions resemble A-level questions, but how will they be marked? I've had to mark AS course work numerically without any idea what the equivalent grade would be."
John Dunford, general secretary of the Secondary Heads Association, said awarding bodies had done little to inspire confidence in schools about grade boundaries.