More than 200 pupils may have to return to school for lessons due to a shortage of laptops, a head teacher has warned.
Jane Girt, from Carlton Bolling College in Bradford, said having so many pupils in school would "defeat the object" of closing amid the England-wide lockdown.
Government guidance says pupils without a device may be deemed vulnerable and eligible to return to classrooms.
The prime minister told MPs earlier 560,000 devices were given out in 2020 and a further 50,000 so far this year.
Mrs Girt said her school, which has more than 1,500 students, had received 261 laptops from the government since March but about 50% of pupils were sharing a device with another family member.
She said: "We have about 400 children who are eligible for free school meals and those tend to be the most vulnerable young people and they tend to be the ones who have a lack of access to devices.
"If we find out they are not accessing their learning because they have not got a device we are trying to find one [but if we can't] those children will have to start coming in to school.
"As we've got 400 eligible students you can imagine that some point we may end up with 200 secondary school children on top of my vulnerable and key worker children...which to me defeats the whole object."
Schools are currently closed to pupils of all ages - apart from vulnerable children and the children of key workers.
According to government guidance, children who have difficulty engaging with remote education at home, such as lack of devices, are not "automatically classed as vulnerable" but "might" fall into the category.
Louise Haigh, Labour MP for Sheffield Heeley, said "at least 5,000" pupils in the city were without a laptop while Ofcom estimates up to 1.78m children in the UK do not have a laptop, desktop, or tablet.
A further 880,000 live in a household with only a mobile internet connection.
Labour leader Sir Keir Starmer urged Prime Minister Boris Johnson on Wednesday to address the issue with "real urgency".
Ms Haigh said: "We've known that a lockdown was coming, we knew that school closures were inevitable... so they could have made sure that these laptops were in place long before closures were announced."
Addressing the House of Commons, Mr Johnson said the government would do "everything possible" to support the move to remote learning and paid tribute to the teachers, parents and pupils for their efforts in adapting.
He also announced the government had partnered with a number of major mobile phone operators to offer "free mobile data to disadvantaged families to support access to educational resources".