Schools are re-opening across the country on Thursday following the Christmas break.
It comes amid concern about the impact high COVID-19 infection rates will have on staffing levels and student attendance.
Teacher unions have warned that thousands of staff are likely to be absent.
Kathryn Corbett is principal at Bishop Galvin National School in Templeogue, Dublin.
She told Newstalk Breakfast sport teachers will be in covering classes.
"It's been a very challenging week, I suppose, in terms of staffing for school.
"We have 10 staff members out of 37 out today - and I did manage to secure two subs.
"So almost all my sport teachers will be in class today covering, so we'll have very limited additional support for children with special needs today".
And she says there is no provision for children who are unable to get to school.
"I'm happy and glad to open the gates, but I'm also thinking of all the children who are at home today - who are isolating or maybe can't come to school, have a vulnerable family member.
"There's absolutely no provision for their education today, so I'm thinking of those children this morning also.
"We're almost two years into the pandemic now, and we've learnt a huge amount in terms of what's needed for remote learning and for in-person learning.
"But we do need structures and supports in place to make that possible."
'I don't think we've planned for it'
She believes investment has to be made in remote learning to make it accessible for everyone.
"Certainly for older children a hybrid model of learning was certainly possible; but also I suppose looking at staffing and who's available, that would be a huge concern.
"You'd have to seriously invest in technology in schools to make it accessible...for everybody
"I don't think we've planned for it, I don't think the supports have been in place for it.
"The narrative has been very limited - 'schools open or closed' - and that's been it, that's been the conversation over the last couple of months."
Alan Kelly is principal of Scoil Mhuire Naofa in Carrigallen, Co Leitrim.
He says a quarter of his teaching staff are absent - and he is awaiting more antigen results.
"We have 25% of our teaching staff will not be able to attend due to COVID.
"We're also down one bus escort for pupils who travel to our special classes in our school as well.
"Thankfully all of my SNAs currently are in a position to attend work, but I'm also waiting on results of antigen tests for all the other staff members".
Mr Kelly says he was lucky with a substitute teacher before Christmas.
"We're in the fortunate position that we have a wonderful substitute who was working with us in the run up to Christmas.
"And myself and the board of management took the decision to employ that teacher for the month of January to do class hours.
"It appears that teacher now, instead of doing the class hours, is going to be used as a stop-gap measure wherever we deem to prioritise in the coming days and weeks."
But he says he could not secure any more substitute teachers "over the course of an hour and a half" on Wednesday.
"We are open, all our classes will be open, but most likely our SET team and myself as admin principal will be covering where needed this morning.
"That's assuming that I have a full cohort of staff I think I have - that's without anyone else telling me that they're unavailable due to COVID or isolating".