Next year's GCSE and A level exams may need to be "tailored" to recognise disruption to teaching and learning caused by the coronavirus outbreak, heads have said.
The idea that pupils might repeat a year to catch up on crucial stages of their education is "not really a credible option" as it would create a "logistical nightmare", according to the Association of School and College Leaders (ASCL).
Geoff Barton, ASCL general secretary, told Tes that it may be necessary to adjust GCSEs and A levels due to be taken next year, to "recognise that it may not be possible to cover all content in the normal way".
Coronavirus: Some GCSEs could have no autumn exams
While he said "we be careful not to over-react", as the shutdown has so far only impacted four weeks of term-term education, one way of addressing learning gaps that emerge might be to "pare down the content of these qualifications".
"They are very content-heavy following the reforms of recent years, and we may need to accept that it is just not possible to deliver all of this in these circumstances," he said.
"Exactly how to do this in the best interests of all students would clearly need careful thought."
Mr Barton was responding to comments made by former Ofsted chief Sir Michael Wilshaw on last night's BBC Newsnight programme.
Sir Michael suggested that teachers may have to work weekends and evenings to remedy the impact of school closures – and, if that doesn’t happen, he could see "no alternative but to repeat a year".
But Mr Barton said the premise that there are "only two options" is "too simplistic".
He said, if it is safe to do so, certain year groups could be sent back to school in the second half of the summer term to help them catch up – and there "may be a role for activities such as summer schools" to cover lost ground.
However he stressed that "we cannot predicate our response on this sort of provision", and staff and students must be given the opportunity to rest after an "intense and demanding" period.
"Sir Michael has the right intentions at heart, but his premise that there are only two options – either for schools to open at weekends and during holidays to help children catch up, or to repeat a year – is too simplistic," Mr Barton said.
"We don't yet know what the learning gaps will be as a result of the coronavirus lockdown, and we will need to gear our response accordingly.
"Repeating a year is not really a credible option, as it would create a logistical nightmare in a system which is built upon children progressing from one stage to the next."
He added: "If it is safe to do so, we may be able to bring back certain year groups which are at crucial stages of education in the second half of the summer term, to help them catch up.
"We may also need to tailor GCSEs and A-levels which are due to be taken next year to recognise that it may not be possible to cover all content in the normal way.
"And we will clearly need to put a particular focus on identifying learning gaps for children from disadvantaged backgrounds and identify extra support.
"There may be a role for activities such as summer schools but we cannot predicate our response on this sort of provision, and we do need to rest staff and pupils after a period which has been intense and demanding, so they are refreshed and ready for the challenge of restarting in September."
An Ofqual spokesperson said: "We know the Covid-19 outbreak will have caused stress and uncertainty for many students, regardless of whether or not they were expecting to take exams this year.
"Students who are studying GCSE, AS or A level courses, but are not due to take exams until 2021, will have had their teaching and learning disrupted. We do not yet know for how long this disruption will continue.
"We are working with the DfE, the wider sector and exam boards to consider the options for next year."