Video report by ITV Cymru Wales Political Editor Adrian Masters
Pupils aged three to seven will return to school from February 22, the education minister has confirmed.
The Welsh Government had previously stated its intention to begin phased re-openings after half term, with Kirsty Williams confirming the news today.
Speaking at the press briefing, she told journalists: "Sadly, we are not yet in a position to be able to see a full return to school for every learner.
"However, thanks to people following our national guidance, there is a sufficient headroom for us to bring back some of our learners in a phased, flexible and progressive way.
"After half term, from 22nd February, our Foundation Phase learners will start to return to school during that week."
The youngest learners have been prioritised because they find it difficult to learn remotely, and transmission risks are lower, the minister said.
Ms Williams added: "Small numbers of vocational learners, including apprentices, will also be able to return to colleges. Again, this is because of difficulties with remote learning, as they will need to access training or workplace environments in order to undertake their practical qualifications."
Children of critical workers and vulnerable learners, as well as those taking exams or assessments and learners in special schools, will continue to be able to attend as they have done throughout the pandemic.
Additional safety measures will be put in place for staff, including twice-weekly testing, the minister said.
But daily contact testing in schools and colleges - where staff and pupils are tested for seven consecutive days after being in close contact with a Covid-positive person - will be paused.
The Welsh Government said it has been put on hold until more is known about the new Covid variants and how this might impact on transmission.
An additional £5m will be provided to support schools, colleges and local authorities to invest further in items they need to keep their premises safe.
Following the announcement, First Minister Mark Drakeford said getting younger pupils back in schools was the "first step" in resuming face-to-face teaching in Wales, with talks due next week on planning a return for older year groups.
Primary and secondary schools would look to use a blended learning model - where pupils mix between face-to-face and online teaching - when older age groups are allowed to return to the classroom.
Mr Drakeford said: "We will want to try and give the profession, the parents especially, as much certainty as we can about what would happen if we were in a position to go further.
"That is not to say that it will mean a return for every child, every day, to the classroom.
"We're going to have to be probably more flexible than that, and try to combine as much face-to-face teaching as we can manage with continued emphasis on safety and wellbeing.
"It may be that not every child is in school every day.
"But it shows that every child is in school some of the time."
The Welsh Government's announcements on Friday drew a mixed reaction from education unions.
National Education Union (NEU) Cymru's senior Wales officer Gareth Lloyd said Ms Williams had taken a "sensible approach" in allowing a flexible return after half term.
Mr Lloyd said: "Our members want a wider return in a safe working environment and we are expecting discussions next week with Welsh Government to ensure robust mitigation measures are put in place."
However Laura Doel, director of school leaders union NAHT Cymru, said members were "bitterly disappointed" the decision had been imposed "whilst there are too many questions left unanswered".
Meanwhile, the education minister stressed that a return to the classroom does not mean a return to out-of-school activities, such as sleepovers, birthday parties and playing in the park.
"We don't want parents to misinterpret this," she said.
"We are told time and time again that our education premises are safe, but it is the added movement around them that contributes to the R number.
"So I must make a plea to all learners, parents and carers - please continue to follow the guidelines."
Wales has now passed the half a million mark for vaccinations, it was announced on Friday.
Deputy chief medical officer Dr Chris Jones said we are seeing a "steady and consistent fall" in the weekly number of new cases of coronavirus in Wales.
"We’ve fallen back from the peak of 650 cases per 100,000 people to around 127 cases today," he said.
"In fact, cases are now lower than at previous points when schools were fully open.
"This is really encouraging, particularly given the presence of the new variant, and is the result of everyone’s efforts and sacrifices over the last seven weeks."