Downing Street suggested that teachers and other staff who refuse to turn up in schools over safety concerns will be a matter for heads to sort out.
Asked whether they would be deemed to be in breach of their terms of employment, the Prime Minister's official spokesman said: "Head teachers I'm sure will be having conversations with their own staff in the usual way.
"The Education Secretary has been working very closely with schools and unions for the last 10 weeks. He met with the unions again yesterday.
"Our approach throughout this has been to work closely with schools, heads, and teachers' representatives to ensure that we deliver a cautious and phased return in a safe way.
"But I'm sure head teachers will have been having discussions with individual teachers."
The majority of primary schools are expected to open up to more pupils from Monday as part of the easing of lockdown but unions remain concerned about the safety of their members.
Schools, colleges and nurseries closed more than nine weeks ago due to the Covid-19 outbreak, remaining open only for vulnerable youngsters and the children of key workers.
But from Monday schools will begin resuming with Reception and Years 1 and 6, despite safety concerns from teaching unions.
The Prime Minister announced that England had met the five tests which will allow an easing of the lockdown including the reopening of some shops and letting people meet in parks in groups of six.
People can also now meet in gardens as well as in the park.
He told the daily Downing Street press conference: "I cannot and will not throw away all the gains we've made together and so the changes we're making are limited and cautious.
"It's thanks to the caution you've shown so far that all five met are being met.
"The result is that we can move forward with adjusting the lockdown in England on Monday."
