Some year groups in England will return on 1 June, with others going back two weeks later, he says.
Scientific advice has failed to reassure teachers that it is safe to open schools on 1 June.
A snap-shot survey of councils in England reveals only a minority are advising schools to reopen on 1 June.
What do you do if your home is in lockdown, but your child's school is set to re-open?
A charity says the most vulnerable children and young people in society are suffering with isolation.
Cambridge University has said there will be no face-to-face lectures during the next academic year.
More than 35 councils warn not all of their primary schools will be ready to reopen on 1 June.
There will be no face-to-face lectures in the next academic year due to coronavirus, the university says.
Thirty organisations write to the prime minister, calling for more support for young people.
Watchdog says universities must tell applicants whether campuses will reopen in the autumn.