Schools and universities are calling for urgent clarity from the government after the announcement that GSCEs and A-Levels in England and Wales will be cancelled amid the coronavirus crisis.
Schools in the UK will close their doors on Friday except for vulnerable pupils or children of key workers.
Universities UK said pupils should not lose the chance to go to university this year because of the move.
The government says there are plans to ensure children receive qualifications.
It comes as the UK death toll rose by 33 to 104 on Wednesday.
Announcing the closure of schools in England on Wednesday, Education Secretary Gavin Williamson told MPs officials were working with exam boards “to ensure that children get the qualifications they need”.
Scotland and Wales earlier said schools would close from Friday while schools in Northern Ireland will close to pupils today and to staff on 23 March.
This academic year’s exams, which were due to take place in May and June, will not go ahead in England and Wales. Decisions are due to be made in Scotland and Northern Ireland.
Schools supporting key workers’ children will be expected to remain open during the Easter holidays, while officials are considering who is classed under this category.
Staff and pupils may be required to work at or attend schools other than their own.
Nurseries, private schools and sixth forms are also being told to follow the guidance to close.
School closure is something the health officials advising government have been continuously asked about.
Their stance has always been that while it can suppress a peak – a 15% reduction has been put forward – some of the gain would be offset by the fact children will still mix outside of school. Parents, including health workers, may have to take time off work or grandparents – one of the vulnerable groups they are trying to protect – may have to look after them.
What is more, children are the age group least likely to get severe symptoms – only 0.2% of cases end up in hospital.
In the end it has undoubtedly come down to two factors.
Firstly, it might just do enough to ensure the NHS is not overwhelmed – as suggested by the new modelling by Imperial College London published on Monday.
Secondly, practicalities – increasing numbers of teachers and children are having to isolate at home and classes and exams would be seriously disrupted in the coming months regardless of what was done.
Alistair Jarvis, chief executive of Universities UK, said the sector was still waiting for more information on exam cancellations and it was committed to working with the government, school leaders and exam regulators on the “practical implications” of the move.
He added that the body hoped there would be “clarity” as soon as possible.
The decision to close schools was welcomed by teachers’ unions but many called for more detail from the government.
Paul Whiteman, general secretary of the National Association of Head Teachers, said there were “many complicated issues to address” and “we have more questions than answers at the moment”.
Parents contacting the BBC expressed their concern that predicted grades might be used for results at GCSE and A-level, if pupils did not sit exams.
Lone parents and those who are self-employed were also worried about coping.
Victoria, in Belfast, said: “I am a self-employed mother of twins. I have zero support.
“Now I have to stay home and look after the children. Where will the money come from?”
By Hannah Richardson, education correspondent
It was the announcement the government did not want to make – shutting down schools indefinitely.
But as the virus spread its claws further into communities it became inevitable.
Heads and teachers are just as at risk as anyone else, and as more and more staff called in sick – increasing numbers of schools started to fall like dominoes under the weight of this pandemic.
Although the decision gives certainty for now – doors will be closed – there is even more uncertainty ahead.
How long will they remain closed? How will pupils cope with learning from home? Who will look after them?
And how will schools manage in their new role as the nation’s babysitters for the children of key workers?
Meanwhile, Transport for London (TfL) announced up to 40 Underground stations would be shut on Thursday and a reduced service would run from Friday.
Mayor of London Sadiq Khan said Londoners should be avoiding using the transport network “unless absolutely necessary” but it would remain open to help frontline health workers.
It came as the prime minister said he would not rule out imposing further restrictions in the capital, where the virus is spreading faster than other parts of the UK.
The Army is also preparing to provide support during the pandemic, with the number of troops in a heightened state of readiness to be doubled to 20,000 and Reserves to be placed on standby to support public services in a new “Covid support force”.
The Ministry of Defence is also planning to put 150 military personnel into training to drive oxygen tankers around the country to support the NHS.
Later on Friday, emergency laws will be introduced in Parliament to provide new powers to deal with the outbreak.
The wide-ranging bill includes provisions for border controls, ways of boosting the NHS workforce and making it easier to register a death.
The government says the measures contained within the Coronavirus Bill are proportionate, will only be used when necessary and have a time limit of two years.
But Labour is calling for a fresh vote on the legislation every six months – describing the plans as “far-reaching”.
Boris Johnson said the subsequent decision to close schools was necessary to further slow the spread of the virus.
Confirmed cases in the UK rose to 2,626 on Wednesday, from 1,950 on Tuesday.
There have been 56,221 tests carried out in the UK for Covid-19. The government says it plans to more than double the number of tests being carried out in England to 25,000 a day.
Meanwhile, Asian nations including South Korea, China and Singapore are facing a second wave of the virus, spurred by people importing it from abroad.
China, where the virus first emerged, reported no new domestic cases on Thursday for the first time since it started recording numbers in January. However, it reported 34 new cases among people recently returned to China.
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