South Yorkshire students are gearing up to find out their GCSE results this morning.
Under the biggest shake-up of exams in England for a generation, traditional A* to G grades are being gradually replaced with a 9 to 1 system, with 9 being the highest mark.
English and maths - key GCSEs for all teenagers - are the first to move across to the new grading system, with other subjects following over the next two years.
The grading switch is part of wider reforms designed to make GCSEs more rigorous and challenging.
England's exams regulator Ofqual has previously estimated that around two per cent of 16-year-old students in England will score a grade 9 in GCSE language, while around three per cent of the group will get the top result in maths.
There are now three top grades - 7, 8 and 9 - compared to two under the old system - A* and A - with A* results now split into 8s and 9s.
Ofqual chief regulator Sally Collier said: "Today's results reflect years of careful planning.
"We have used the same tried and tested principle of comparable outcomes, as in previous years, to ensure that this first cohort of students is not disadvantaged.
"If a student receives a grade 7 today, they could have expected to have received a grade A last year.
"And if they get a grade 4, they could have expected to get a grade C in 2016."
Ahead of the results, the Association of School and College Leaders (ASCL) said reformed GCSEs would leave pupils sitting more exams within a six-week summer exam season, which was likely to put them under intense pressure.
ASCL general secretary Geoff Barton, said: "We have already had reports from members of increased stress and anxiety among pupils this year, and this will intensify next year.
"We know from numerous reports that there is a rising tide of mental health issues among young people and we are concerned the new exams will make the situation worse.
"The new GCSEs are more challenging, and there are more papers, and this is putting severe pressure on young people.
"We support a robust qualification system, but it has to be balanced against the welfare of young people, and we are not sure the balance in the new system is correct."
Schools minister Nick Gibb said: "A new grading system was needed to distinguish between the old and the new reformed GCSEs.
"The new grading system also provides stretch for the highest performers by showing greater distinction between the top marks."