Professor Alan Smithers, director of Buckingham University’s centre for education and employment, said the move is an “eleventh hour desperate measure”.He said: “Schools are judged by these exams so there is a tendency to put too many people in the higher tier, hence the pass mark can be very low. Teachers can choose whether to enter students for the higher tier paper – where the maximum grades are 9s, the top grade which is equivalent to a high A* – or the lower tier paper, where the maximum grades are 5s, which is somewhere between a B and a C.Previously the lowest available grade in the higher tier paper other than a U was 4-3 – which is roughly C-D – but Ofqual said they have now changed this to 3-3, which is roughly D-D. GCSE pupils who failed the new tougher science exam have been handed a free pass by the watchdog after it moved the boundaries, it has emerged. Just days before students across the country pick up their results, Ofqual has taken the highly unusual step of intervening to save science students from failing.The move follows warning from exam boards that a number of students would be given a U, standing for “unclassified”, in their science GCSE which would “misrepresent” their ability. The exams watchdog disclosed on Monday that it has introduced a new “safety net” to prevent too many students walking away with a U, the only grade that signifies a fail.–– ADVERTISEMENT ––The last minute change to the boundaries will affect low ability students who took the higher tier paper in the new science double award exams, where students are examined in three sciences but it counts as two GCSEs. In a blog published on Ofqual’s website, Cath Jadhav, associate director of standards and comparability, wrote: “During the awarding period exam boards reported to us that, while they were confident in standards set at 4-4, there were more students than expected getting an unclassified result on higher tier combined science.“Receiving an unclassified result because they had been entered for higher tier would have misrepresented their ability.”She went on: “Therefore, we decided to allow exam boards to use grade 3-3 on the higher tier for this summer, matching grade 3-3 on the foundation tier.”“Senior examiners in each of the exam boards have reviewed the work of students at this grade and confirmed that it is of an appropriate standard.”In total 372,000 students were entered for science double award, according to Ofqual’s provisional data, but they declined to specify how many students the change of grade boundary will affect. “This year it looks as though that hasn’t even worked and so they’ve bought in this extra grade. One questions the wisdom of having a tiered entry in the first place.“With the wisdom of hindsight they ought to have considered this and put in something in place. Now they have to go at it at the last minute.”Of the 5.1 million GCSE exams that were taken this summer, around 90 per cent were the new, “tougher” courses, which were part of reforms instigated by former Education Secretary Michael Gove.Coursework axed in many subjects and curricula broadened, as part of an attempt to inject rigour into the qualifications and bring the UK in line with top performing countries in the Far East.Only the new English and Maths exams were sat last year, with another 20 subjects added this summer under a numerical grading system of 9 to 1 instead of A* to G. As part of its exam reforms, the old science and “additional science” GCSEs have been replaced with a new double award GCSE in “combined science”. Want the best of The Telegraph direct to your email and WhatsApp? Sign up to our free twice-daily Front Page newsletter and new audio briefings.