Teenagers await GCSE exam results
Nearly 700,000 pupils in England, Wales and Northern Ireland are receiving their GCSE results, as schools face tougher targets on pass rates.
Some 40% of a school's pupils are now expected to get five A* to C grade GCSEs - up from 35% last year.
And changes are under way to stop grade inflation and ensure pupils have a thorough grasp of spelling and grammar.
The proportion of entries awarded top grades has risen every year since GCSE exams were first taken in 1988.
Graham Stuart, the Conservative chairman of the education select committee, said: "The standard of performance is better than it's ever been, the teaching is better and the children are cleverer than ever before.
"The key question is, are (GCSEs) fit for purpose today?"
Last year 70% of entries to GCSE exams, which replaced O-levels and CSEs, were awarded between an A* and a C grade.
A total of 658,000 16-year-olds across England, Wales and Northern Ireland will receive their results on Thursday. A further 547,000 candidates, many of whom will have sat exams a year early or as adults, will also receive their grades.
In an attempt to address concerns of "dumbing down" and ensure results are comparable, the exams regulator for England, Ofqual, has told exam boards they will have to justify any results that are notably different to previous years.
Changes in England
Ofqual has also announced changes to GCSE courses starting this September.
All exam entries from 2014 in English literature, geography, history and religious education will also be assessed for spelling, punctuation and grammar.
Also, modular or unitised GCSEs - where assessments can be taken throughout the two years - are to be dropped in England.
Pupils starting courses this September will have to sit all their exams at the end of the two years, in the summer of 2014.
Modular GCSE syllabuses were first phased in under the previous Labour government in 2009.
But in Wales, schools will be able to choose between the two styles of GCSE assessment - linear or modular; meanwhile a review is under way to see if the system needs to be changed or improved.
In Northern Ireland, following a 12-week consultation, ministers have decided to stick with modular exams.
Most pupils in Scotland take Scottish Standard Grade and Higher qualifications, rather than GCSEs and A-levels.
They received their results earlier in August.
Grade inflation has been a concern for England's Education Secretary, Michael Gove, who has called for an end to "a culture of re-sits".
It is understood that, longer-term, Mr Gove wants to get rid of GCSEs completely - replacing them with exams similar to the old O-levels and CSEs.
But this is not supported by the Liberal Democrats - the Conservatives' coalition partners - and many teachers have reservations.
Mr Stuart told BBC Radio 4's Today programme: "The key question is are they fit for purpose for young people and for the economy. A recent report said they needed fundamental reform...and the cross-party committee I chair supported that."
He pointed out that last year 42% of pupils did not achieve five good GCSEs and he said "that needs to inform the debate".
Mr Stuart said he also wanted to see a national syllabus across the country.
The Association of Teachers and Lecturers (ATL) education policy adviser Adrian Prandle said: "We hope thousands of students get the results they want on Thursday and can celebrate two years of hard work.
"However, ATL urges the government not to blunder around chopping and changing exams in isolation from the curriculum and without taking account of all the evidence and research.
"It would be a dreadful mistake to return to a two-tier system with revamped O-levels and CSEs."