Addressing Holyrood during her Covid update, Ms Sturgeon announced the new planned date for pupils to return to school in Scotland will be February 1.
Pupils were planned to be back in classrooms from January 18.
However, Ms Sturgeon noted the new planned return date would be reviewed in mid-January.
Ms Sturgeon said in her statement: “I can confirm that we have now decided to extend that date and keep schools closed to the majority of pupils until February 1.
"We will review this again in mid January.
“The change will apply to all pupils – except vulnerable children and children of key workers. And it includes nursery schools, as well as primary and secondary schools.”
Ms Sturgeon said this was ‘the most difficult of all decisions’ for the Government to make.
Announcing a raft of changes to coronavirus restrictions, including a new period of lockdown for areas in level four, the First Minister said a period of home learning would drive down transmission rates.
She also said the scientific community was not clear on the impact of the new variant of Covid-19 on young people.
Ms Sturgeon said: "Just as the last places we ever want to close are schools and nurseries, so it is the case that schools and nurseries will be the first places we want to reopen as we re-emerge from this latest lockdown.
"They remain our priority."
The First Minister also said that work was being done to see if school and childcare staff could be made a priority for vaccination.