BRINGING all pupils back to school before the end of the month is "asking a lot" of principals and teachers, it has been warned.
Head teachers have said there remain concerns about health and safety for children and staff.
Education minister Peter Weir has said all schools will reopen in full for the new term, with social distancing largely abandoned in favour of `bubbling'.
Mr Weir said a five-day-a-week return was what parents wanted and was "the best outcome for children".
However, teaching unions said the relaxation of social distancing requirements was a "cause of deep concern".
There are also fears about safety on home-to-school transport where children from different schools cannot be kept apart.
Schools have been closed since March with most young people learning from home.
Pupils from P1 through to third year in secondary schools will return for the new team in bubbles. There will be efforts to minimise movements between classes for Years 11 to 14.
Mr Weir has said that face coverings in schools are not "necessary or implementable" at this stage.
Chief Scientific Advisor Professor Ian Young has told the minister that there may be "some benefit" to the use of face coverings among older children depending on the context.
The new guidance agreed by the executive represents a significant change from the original plan that recommended children return with one-metre social distancing.
Many schools had been planning to bring pupils back part-time due to the requirement to keep them apart.
Updated guidance will be issued next week.
Barry Mulholland, chief executive of the Controlled Schools’ Support Council, said there was no doubt that everyone working in education wanted a full return.
"The challenges continue to be extensive and complex with a situation that can change on a daily basis. To date, collaborative working across all the organisations who support schools has proved effective," he said.
"The reality is that we are asking a lot of our dedicated principals, teachers and support staff. They will need continued support and the understanding of all but most importantly, the trust and support of parents, to implement this new way forward.
"This approach remains the key to achieving the most successful outcomes for all, with children and young people’s best interests remaining the central focus."
Peter Friel, principal of St Pius X College in Magherafelt, said there was still a "great deal of uncertainty" around how pupils returning would work.
"Those who are older are slightly at greater risk, but even the idea that classes will stay within the rooms will create huge problems within a secondary school," he told the BBC.
"I cannot envisage in my own mind how that would work at St Pius, when kids go to science have to go to a science lab, when they go to technology and design they have to go the technology department."
While bubbles will operate in schools, there also are worries about how transport will work.
Typically buses are used by children from different year groups and different schools.
Sinn Féin councillor Sheamus Greene, who drives a school bus in Fermanagh, said he did not think the return had been thought through.
Mr Greene said he could have up to 45 children from eight schools on his bus at any one time.
"We have got no information since the lockdown, My major concern is that a lot of drivers in Fermanagh are in their sixties and seventies," he said.
"Over the last number of months I have been raising this. Nothing has come back."
