Schools across Britain are struggling to stay open as staff and students stay at home because of the spread of coronavirus.
The closures come amid confusion about why schools are being advised to stay open when the government has stepped up advice to curb social contact to try to slow the spread of the virus.
Geoff Barton, the general secretary of the Association of School and College Leaders union, said head teachers were saying they were struggling to keep their institutions open beyond Friday.
"Some very seasoned head teachers have been calling me to say they will not be able to manage much longer," he told the BBC.
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"One said he had 17 members of staff call in sick. And I think this will be replicated around the country."
Some schools are closing but offering to look after the children of parents who work in key public services like health or social care.
Patrick Vallance, the government's chief scientific adviser, defended the policy before a parliamentary committee on Tuesday, saying that school closures were "on the table", but not a step the government should be taking at this time.
This comes as angry parents are refusing to send their children to school and are complaining that other countries were doing more to stop the spread of coronavirus.
On parliament's website, a petition calling on the government to shut schools and colleges had attracted more than 671,000 signatures.
