The government is adamant schools will be safe to open in September, amid claims it has not given enough clarity to teachers over new procedures to combat the spread of coronavirus.
Most schools closed at the end of March as the UK went into lockdown, although some remained open for children of key workers and for vulnerable pupils.
More students were allowed to return to schools in England and Wales last month, with the government working towards opening schools as normal in the autumn.
"We have to get children back to school in September," Housing Secretary Robert Jenrick said on Sunday.
"It's so important for the future of our children and for the whole country that they have face to face contact, with their teachers, in the classroom.
"We're working very closely with headteachers and the teaching unions to make sure that all the steps necessary are put in place over the summer so that children can go back in September - and it is an absolute priority for the government."
Mr Jenrick added: "I believe that schools... will be safe, in September."
However, teaching unions are demanding more clarity be given to schools, after Prime Minister Boris Johnson announced a slowing down of the easing of lockdown.
Patrick Roach, general secretary of the NASUWT teaching union, told The Observer: "In light of recent changes to plans for relaxing lockdown measures, the government needs to provide greater clarity to school leaders, teachers and parents about what this will mean for the reopening of schools in September."
To cope with schools being able to reopen in full, a member of the government's scientific advisory group, SAGE, has suggested one trade-off might be to shut pubs.
Minutes released by SAGE reveal that school reopening has been discussed several times by the expert panel, with the group saying on 23 June that there "may be a need to change measures at the end of the summer in order to be able to keep R below 1 whilst proceeding with the planned reopening of schools".
On Friday, chief medical officer Professor Chris Whitty said the country had "probably reached near the limit or the limits" of what can be done to reopen society.
Professor Graham Medley, a member of SAGE, said England may have to consider closing pubs so that schools could reopen.
He told BBC Radio 4's Today programme: "It might come down to a question of which do you trade off against each other and then that's a matter of prioritising, do we think pubs are more important than schools?"
The latest estimate puts the R number, which refers to the number of people on average that an infected person passes the virus to, at between 0.8 and 0.9. However, this refers to the transmission of coronavirus from several weeks ago.
Some local lockdown measures were announced in parts of the North West of England and areas of West Yorkshire this week, following a spike in infections.