A teaching union has called for a combination of online learning and mass Covid testing in Scotland’s schools to ensure a safe return in January.
Its members are concerned that socialising over Christmas will drive up rates of Covid-19, putting staff and pupils at risk.
NASUWT has asked Education Secretary John Swinney to consider the move.
The Scottish government said pilot schemes to test asymptomatic staff would begin in January.
It has not ruled out a post-Christmas lockdown if infection rates rise.
At the daily briefing on Friday, Health Secretary Jeane Freeman said all options remained on the table for Covid lockdown rules after the five-day Christmas easing period ends.
There had been speculation that some areas of the country could have tighter restrictions imposed after 27 December.
Officials in England and Wales have already announced plans to stagger the start of the school term and introduce testing.
However, unions in England have called government plans to get schools to organise their own testing programmes at short notice “chaotic and rushed”.
Northern Ireland is considering some at-home learning in January.
NASUWT has proposed a delay in the physical return to school for all staff and pupils, and the introduction of remote and blended learning, particularly in areas where virus levels are high or rising significantly.
Union general secretary Patrick Roach said: “Remote and blended learning, together with a credible programme of mass testing, could help to ensure that schools are Covid-safe when they reopen next term and help to suppress the transmission of the virus in the wider community.
“It is vital that the government does whatever it takes to prevent a further surge in Covid-19 cases when schools return in the new year.”
Jane Peckham, from NASUWT Scotland, said a delay in the full reopening of schools, blended learning in areas of high virus transmission, and routine testing were the “sensible and responsible course of action”.
Those measures would “protect the welfare, safety and health of pupils, the education workforce and wider community, and also to minimise the disruption to pupils’ learning”, she said.
The Scottish government said the decision not to alter the school holidays was taken on public health advice, but fell to local authorities.
A spokesperson said: “Being in school is in the best interests of children and our priority remains to ensure schools are safe, open and welcoming.
“We are committed to exploring how we can expand testing for schools.
“After the return of the school term in January, a number of pilots will get under way with the aim of establishing a sustainable programme of asymptomatic testing amongst school staff.”
Scottish Greens MSP Ross Greer told the BBC’s Coronavirus Update programme on Friday that he backed teachers’ unions in disputes with local authorities about Covid safety measures in schools.
He said teachers had higher rates of Covid infection than the general population and clinically-vulnerable staff should not have to work in classrooms.
Mr Greer said: “All we’re asking for is reasonable protections, the kind of protections that people in other workplaces are getting.”
The coronavirus pandemic has caused severe disruption in Scotland’s schools in 2020.
Most pupils had at least three months of learning at home during the first lockdown, exams have been cancelled and many students have had to self-isolate for two weeks at a time after coming into contact with someone who tested positive for the virus.
Opposition parties have regularly accused the education secretary of “dithering” over key decisions, which they said had left pupils, staff and parents in the dark.