The first minister says plans in some parts of Scotland for pupils to attend school just once a week are "not good enough" - and insists she will push to have youngsters in classes full-time before next summer.
Local authorities are making plans for schools reopening on August 11.
But some have said pupils may only be able to attend once a week in the earlier phases, or every few weeks on a rota basis, to ensure social distancing can be maintained. The rest of their education would be made up with home learning, often with the involvement of teachers remotely.
At the weekend, John Swinney - the education secretary and deputy first minister - claimed this "blended" approach could last until summer 2021.
But at her daily briefing today, Nicola Sturgeon said she did not want that arrangement to last for a year.
She said: "There has been a suggestion that I've seen by some in the last couple of days that we are somehow planning as if blended learning for the entirety of the next academic year is inevitable.
"I just want to be clear today that that is not the case.
"We do not want this part-time blended model of education to last any longer than it has to.
"And even from the starting point of August 11, we want the home part of schooling to be minimised so that the in school part of education is maximised."
Asked whether she supported plans by some local authorities to have just a day of learning a week, Ms Sturgeon added: "No, I don't think that is good enough.
"I said very clearly in my opening remarks that we have to start from a point of seeking to maximise - absolutely maximise - the amount of time children will spend in a school environment, having face-to-face learning with their teachers."
Ms Sturgeon says she will scrutinise councils' plans and ask them to rethink where necessary.
But the Scottish Conservatives claim her "contradiction" of Mr Swinney's comments has only served to cause more confusion.
Shadow education secretary Jamie Green said: "Parents and teachers won’t know who to listen to - the first minister or the education secretary - as their stories are increasingly different.
"Councils are being left in the dark and left in the lurch."