School attendance has plunged into chaos, headteachers have warned, as the proportion sending classes home to self-isolate has doubled in a week.

Between 18 and 20 per cent of schools sent 30 or more pupils home last week to isolate, up from 8-9 per cent the week before, according to the latest official data published by the Department for Education (DfE).

 Almost two thirds (64 per cent) of all secondaries in England sent at least one pupil home last week, up from 38 per cent the previous week. Fewer pupils were sent home from primaries, but the proportion had doubled in a week from 11 per cent to 22 per cent.  

Headteachers said that schools across the country are now operating a “chaotic rota system by default”.  

Geoff Barton, General Secretary of the Association of School and College Leaders, said: “Disruption is widespread and is happening in an ad hoc manner because of the unpredictability of outbreaks.  

“This makes it very difficult for schools to be able to plan and deliver lessons and catch-up support. This is exacerbated if there are also members of staff having to self-isolate.  

“We understand the government’s desire to keep all pupils in school full-time.But when nearly two-thirds of secondaries are sending home pupils we have a chaotic rota system by default.”  

Mr Barton urged ministers to allow schools to formally move to a “planned” rota system – where students are in the classroom one week on, week off – arguing that this would be in the “best interests” of pupils.  

Meanwhile, the National Education Union, accused ministers of “squandering” the opportunity to reduce coronavirus rates and failing to make enough tests available.  

Kevin Courtney, joint general secretary of the union, said: “Schools and families are now having to deal with the reality of rapidly increasing disruption in schools as coronavirus infection spreads through the school population.”

 Secondary school attendance overall dropped to 83 per cent last week, down from 87 per cent the previous week.  "The drop in attendance is mainly due to the increased number of pupils self-isolating due to potential contact with a case of coronavirus,” DfE said.

School attendance varies widely across the country, with some areas hit worse than others.  Hull’s director of public health Julia Weldon warned on Tuesday that more than half of schools in the city have seen closures in some year groups due to coronavirus.  

Headteachers in the city have asked the Health Secretary to allow them to close for all but vulnerable children and the children of key workers as they struggle to cope with staff absences.  

They said they want to keep schools open but that “as a matter of some urgency” some need to be able to restrict attendance “in order to maintain high quality provision and the morale of all those in education”.  

The city’s three Labour MPs warned Matt Hancock that coronavirus rates are at “alarming” levels in the community adding: “There is a concern that if children of key workers cannot be prioritised for attendance there will be a major threat to the infrastructure in the city.”  

A legal duty on schools to provide good quality remote education for self-isolating pupils came into force last month.  The Government used emergency powers to issue a directive to schools to ensure children at home have immediate access to remote education that it "aligns as closely as possible" with what their peers learn in the classroom.

 But the Scientific Advisory Group for Emergencies  has said that prolonged periods of remote learning are “likely to result in poorer educational outcomes” for pupils, according to international studies.  

A DfE spokesman said: “Over 99 per cent of schools have been open every week since term began and millions of pupils are continuing to benefit from being in school.  

“The Chief Medical Officer remains of the view that schools should remain open, and has highlighted the damage caused by not being in education to children’s learning, development and mental health.”