Speaking on the BBC's Good Morning Scotland radio programme on Wednesday, Mr Swinney said there has now been a “sustained reduction” in levels of Covid-19 across the country, which enabled him to announce on Tuesday plans for children to return to the classroom full-time from August 11.
His change in stance came after the Scottish Government's initial plans for blended learning - which could have seen youngsters in school for as little as one day a week in some areas - had come under fire from parents.
Ten days ago, Mr Swinney said it was "unlikely" schools would return to normal within the next academic year.
But on Tuesday, he told Holyrood that schools should be able to reopen to all pupils from August 11, so long as the spread of the disease “is sufficiently low to provide assurance that we can continue to control the virus”.
Blended learning will be the Scottish Government's “contingency” if it is deemed unsafe for schools to reopen without social distancing, he added.
Opposition politicians branded the move the “mother and father of ministerial climb-downs”, and accused the Government of a “screeching U-turn”.
But Mr Swinney insisted the change in stance was possible because of “a sustained reduction in the level in infection in our society”.
He said “faster progress” in containing the virus is being made than ministers had envisaged when the four-phase route map out of lockdown was announced in May, insisting “we are in a brighter position than we were then”.
He said: “We have also seen rapid progress being able to be made in the relaxation of lockdown, because of the level of compliance from members of the public.
“As a consequence of that we assess that by the time the schools are due to come back in August, we will be very significantly into phase four of our route map, and as a consequence of that there is every reason why we should try to resume full-time education for all students within Scotland.”
Scotland is currently in the second phase of easing lockdown restrictions, and Mr Swinney said the relaxation of measures has "thankfully" so far not resulted in a rise in infection levels.
“People have accepted the relaxation of lockdown, they have continued to comply with the general measures that are in place to reduce infectiousness and as consequence we find ourselves in a stronger position,” he said.
“So we now feel safer to make that judgment that we can restore full-time education in August, which was always a desire for us to restore full-time education at the earliest possible opportunity.
“We've gone from 20,000 people capable of transmitting the infection to 2,000 in the space of about a month.
“We want to make continuous progress to erode those numbers so we really are suppressing the virus.”
He thanked teachers for their efforts to develop blended learning plans for schools, saying there is now a “strong” contingency plan in place.
He also warned individual schools may have to close in future if they have a Covid-19 infection.
A message from the Editor:
Thank you for reading this story on our website. While I have your attention, I also have an important request to make of you.
The dramatic events of 2020 are having a major impact on many of our advertisers - and consequently the revenue we receive. We are now more reliant than ever on you taking out a digital subscription to support our journalism.
By supporting us, we are able to support you in providing trusted, fact-checked content for this website.