Not all secondary school pupils will return to the classroom on Monday a union leader warned.
Geoff Barton from the Association of School and College Leaders said that secondary school reopenings are likely to be "staggered" as pupils take covid tests before returning to school.
He told BBC Breakfast that for primaries it will likely feel "pretty normal" from next week.
But on secondary schools and further education, he said: "I think for secondaries you've got the issue of the testing, which means there is inevitably going to be a bit of a staggered start because those young people won't be able to go into their classroom until the first of those tests has been done.
"Over the first two weeks they need three of those tests and then the responsibility moves back to the home."
Mr Barton added: "If we see next week for secondary and further education young people as a transitional week of starting to bring them back into school, starting to teach them how the testing works, the week after that, starting the 15th, is going to look as normal as it might do."
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Calum Semple, professor of outbreak medicine and child health at the University of Liverpool, said that after children have performed Covid-19 tests under supervision, they "get used to it".
He told BBC Breakfast the package of measures such as increased ventilation, masks and tests means schools "can be safe".
He said: "The good news is we're finding quite low rates of active infection within the schools.
"We're using the lateral flow antigen tests that identify those children that are most likely to be infectious - and about 1.2% of school pupils are testing positive and about 1.6% of staff are testing positive.
"It is really low in most occasions - sometimes in some areas it's down to 0.4%.
"So, as a game-changer, it is giving confidence that schools are safe."
