Schools face an "ongoing and considerable challenge" in keeping open during the Covid pandemic, a top Department for Education official has admitted.
The National Schools Commissioner Dominic Herrington also said today that there was a consensus about the importance of keeping all schools open.
His comments at the Schools and Academies Show comes as new figures show almost two-thirds of secondaries have pupils off because of potential contact with a confirmed Covid case at their school.
The government now faces calls from local leaders and headteachers to be more flexible about its decision to keep all schools fully open during the pandemic.
Mr Herrington said: "We know there is an ongoing and considerable challenge in keeping all schools open and, as I said earlier, we all believe that is the most important thing. There is no substitute for face-to-face teaching and the face-to-face experience of being in school."
Giving a talk on the challenges presented by Covid-19 at the Schools and Academies Show, Mr Herrington said: "I think the main thing is that all schools have stayed open and that children have been safe. Since September, over 99 per cent of schools have been open."
His comments come as Boris Johnson has been called upon to allow partial school closures in a city where Covid-19 infection rates are the highest in the country and have risen at an “astonishing and terrifying” rate.
Leader of Hull City Council, Stephen Brady, has written to the prime minister urging him to allow “more local freedom and flexibility” in restrictions around schools.
Last week, Hull’s public health chief said schools in the city were "straining to stay open" because of the rising number of teachers with Covid or self-isolating.
The latest figures from the DfE show the number of schools with pupils off self-isolating because of potential contact with a coronavirus case has almost doubled in just seven days.
The Association of School and College Leaders has warned that schools are operating on a "chaotic rota system by default".
Widespread disruption is happening in an "ad hoc manner" because of the "unpredictability of outbreaks", making it "very difficult" for schools to plan and deliver lessons, according to ASCL.
Its general secretary Geoff Barton said schools need to be given more latitude to move to a planned rota system "if they feel that this would be less disruptive, more manageable, and in the best interests of their pupils".
Before the academic year started, the DfE has said moving schools onto rotas was part of its plan for managing local outbreaks of Covid in the "worst-case scenario".
However, despite now being in a national lockdown, no schools have been moved onto rotas by the government to date.