The coronavirus infection rate in Scotland needs to be "substantially lower" than it currently is before pupils can return to schools, according to the Deputy First Minister.
John Swinney told STV's Scotland Tonight programme that a careful balance needs to be struck for pupils being allowed to return - which would also have a knock-on effect on their parents returning to work.
Mr Swinney, also the country's Education Secretary, discussed the reduction of the R number which had been the subject of First Minister Nicola Sturgeon's briefing earlier on Thursday.
The number is currently believed to be below one - meaning each person infected with Covid-19 passes it on to less than one other person, having been above three at the start of the lockdown.
Mr Swinney said: "There's going to be a very careful management of this issue across the whole of government, because one of the key considerations.
"I can't just sit down one day and say the schools are going back. I have to be absolutely mindful of the sciences involved.
"Your viewers will have probably heard the First Minister talking at lunchtime today about the R number, the reproduction number of coronavirus.
"We need to get that substantially lower than it is today before we can even contemplate bringing any pupils to our schools because obviously if we do that it affects parents going back to their work.
"It's a really careful balance to be struck because what we don't want to do is to undermine the really good work that's been done by a commitment of members of the public to reduce the incidence of coronavirus in our society.
"We have to reflect those in our decisions about Scottish education, just as much as they have to be reflected in the business communities as well."
The deputy FM also reiterated that whenever pupils do return to classrooms, it would not be done all at once.
Plans are still being discussed with an education recovery group which will be meeting again virtually on Friday.
He added: "We've made no definitive plans when schools will recommence and we've made no changes to the arrangements for the forthcoming period.
"What I can say definitively is that I kind cannot see a situation where all pupils in all schools will come back in one go.
"I just can't see that happening - for all the reasons of social distancing and the gathering together of many pupils in one individual school.
"We couldn't have 2,000 pupils coming back together again in some of our secondary schools in Scotland.
"So there'll have to be a phased return for different groups within individual schools - and the education recovery group is actively looking at what that might look like."
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