GCSE grades will be scrapped and replaced with a numbered scale with coursework being removed completely from some subjects, in the biggest upheaval for decades.
The move will also see one more grade added into the system as part of a bid to distinguish between the brightest students.
England's exams regulator Ofqual said that under the changes , pupils will be graded from one to nine - with nine the highest mark available. There are currently eight grades - A*-G
Currently, in some subjects such as maths and science, high numbers of pupils achieve A* and A grades which makes it difficult to pick out the top students, it was suggested.
Chief regulator Glenys Stacey said that in these cases "you then begin to question whether the qualification is doing its job in differentiating sufficiently your most able students."
In a report on the changes, Ofqual said: "Currently there is a 'bunching' of grades as most students are awarded grades B, C and D. Adding in an extra grade will improve the spread of grades in this area."
As now, in future youngsters who fail an exam will be given a "U" for unclassified.
Ofqual said that the move to a numerical system will also signal that the revamped GCSEs are a new qualification, which it said would be less apparent if the grading system remained the same.
The change, with nine as the highest mark, is also likely to be seen as leaving the door open for an extra grade to be introduced in the future if necessary, also though Ms Stacey stressed that this was not why the system had been chosen.
She insisted: "It is not the case that we are doing it to be able to slip in another grade on top of that."
A consultation on how the new system will compare to the old - for example which number is equivalent to a C - will begin in December, Ofqual said.
The first three subjects to be revamped - English literature, English language and maths - are due to be taught in secondary schools in England from 2015, with the first exams taken in the summer of 2017.
These three subjects account for around a third of GCSEs awarded in England each year.
A year later, in 2016, new GCSEs in science, history, geography and some modern foreign languages, as well as other subjects often taught in schools like RE and art, will be introduced to schools.
The regulator confirmed that it is to consult on the range of subjects that will carry the GCSE title in the future, a move which is likely to fuel speculation that some subjects may not be part of the brand.
Coursework is to be removed from English language GCSE, with the qualification assessed entirely by exam. As with the current system, students' speaking skills will be tested, but will not count towards the overall grade. A fifth of marks (20%) for the written exams will be dedicated to spelling, punctuation and grammar.
English literature will also be assessed wholly by exam, with five per cent of marks given to spelling, punctuation and grammar.
Maths will continue to be assessed by exam only.
"Tiered" papers - which allow some pupils to take an easier exam while others sit a harder one - will be axed for both English subjects but kept for maths.
The exams will also be "linear" - meaning that they will be two-year courses with all exams taken at the end, rather than in bitesize chunks.
Ms Stacey said: "You don't get many opportunities to radically reform qualifications and make them the best they can be, and this is a once in a decade opportunity."
She suggested that the move away from traditional grades may be hard to understand for many people, but added it was important.
"The new qualifications will be significantly different and we need to signal this clearly. It will be fairer to all students that users of the qualification will be able to see immediately whether they did the new or a previous version of the GCSE. The new scale will also allow better discrimination between the higher-performing students."
She added: "We know that there has been some concern in recent days about whether some subjects will continue to be available.
"We plan to consult in the new year on principles for allowing subjects to be included as GCSEs. The aim is not to stop important, established subjects, but rather to make sure everyone is clear about what a GCSE is and is not."
Malcolm Trobe, deputy general secretary of the Association of School and College Leaders, said: "There is much to welcome in today's announcement, especially the measured approach Ofqual has taken to this significant task.
"We have always agreed that GCSE can be improved to better prepare students to meet the needs of the world we live in today. But the constant tinkering with GCSEs we have had in the past has not been helpful.
"Almost all of the changes appear well thought through and ASCL fully supports the phased introduction. Keeping tiered papers in maths is logical, given the nature of the subject and the increased level of difficulty for the most able.
"There will, however, be significant disappointment that the speaking and listening grade is not integrated into the overall grade for English language.
"As the new exams will be very different, the move to a numerical grading scale will help to avoid confusion. It is good to see that the new grading system will only be introduced when a subject syllabus is changed."
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