More than 700,000 teenagers are receiving their GCSE results, in England, Wales and Northern Ireland, amid claims some exams were too hard.
GCSEs in England have been overhauled in recent years to make them tougher. And a new numerical 9-to-1 grading system has been introduced.
Head teachers say some lower-attaining pupils have been so demoralised they refused to sit the exams.
England’s exams regulator insists it is keeping standards the same over time.
Exam boards do this during the marking process by making adjustments to grade boundaries, having married the difficulty of papers with the predicted ability of the group of students sitting the exams.
This means the percentages achieving different grades nationally do not change very much from year to year.
The same process happens in the other nations – but in Wales, where different exams are sat, there is an A*-to-G grading system.
And in Northern Ireland, pupils are receiving their results in a mix of letters and numbers, owing to the combination of examinations taken.
Nearly all respondents to an Association of School and College Leaders survey of 554 schools in England said the new exams, which cover a wider syllabus, were harder.
One deputy head said: « Lower-attaining students are completely demoralised by these exams.
« We have an increasing number refusing to attempt mocks and actual exams.
« This has never happened before. »
‘I cannot do this’
An assistant head said the exams had been designed without a thought for low-attaining pupils or those with special educational needs and disabilities (Send).
He said: « I cannot think of anything more dispiriting than going through school thinking every day, ‘I cannot do this.’ But that is the reality for many students. »
Geoff Barton, the association’s general secretary, said ministers had increased rigour in the interest of the more able students and at the expense of the more vulnerable.
He called for the exams to be tweaked to make them « less of an ordeal » and said a more « humane way » to assess the abilities of young people was required.
There were an estimated 5.2 million GCSE entries this summer – up 50,000 on the previous year.
Education Secretary Gavin Williamson wished students, teachers and parents the best for their results.
« It’s a day that marks the culmination of years of hard work and opens doors that can create life-changing opportunities, » he said.
« The work this government has done to drive up standards means there has never been a better time to go on to further study.
« We will continue to focus on discipline, outcomes and standards, so whatever path they choose, young people will get a better and better education so they can be full of confidence about their future. »
But the National Education Union warned of the impact these tougher exams were having on student mental health and wellbeing.
Assistant general secretary Nansi Ellis said excessive content crammed into too short a time had created an exam system « that is largely about regurgitating facts, with very little time for thinking or deeper learning ».
« Not only does this fail to reflect students’ ability, » she said, « but it is leading to many feeling disillusioned, disengaged and stressed. »
Last week, a leaked document revealed the low number of marks required to achieve a grade A in some A-level subjects.
Teachers and students had already complained about the difficulty of some maths papers in particular.
Are your GCSE results not what you expected? If you didn’t get what you were hoping for, get in touch and put your questions on what to do next to our experts. A selection will be answered in our coverage. Email.
Please include a contact number if you are willing to speak to a BBC journalist. You can also contact us in the following ways:
- WhatsApp: +44 7756 165803
- Tweet: @BBC_HaveYourSay
- Text an SMS or MMS to 61124 or +44 7624 800 100