The school system is being "propped up" by trainee teachers due to a lack of qualified teachers, a school principal has said.
According to an Irish Primary Principals Network (IPPN) survey, Dublin, Cork, Galway, Kildare and Wicklow are the counties most affected by the teacher shortage.
High rents, the cost of living and more lucrative opportunities abroad are some of the reasons that the once attractive profession has lost talent.
Vicky Barron, Principal of CBS Primary School in Wexford town, told The Pat Kenny Show that the southeast is also feeling the pinch.
"Whereas I'm not one of the areas highlighted, we are still having issues down here," she said.
"It's every week, Pat ... all principals are ringing looking for substitute teachers."
Ms Barron said many schools are "being propped up by trainee teachers", as those who are qualified have gone abroad to countries like Abu Dhabi.
"They seem to be getting much better terms and conditions earlier in their career there", she said.
"It is really difficult with the way the education system is laid out, with the way leave is allocated."
"What we're seeing on the ground is that our children are suffering because our teachers aren't with them and we can't find qualified, suitable applicants for some positions."
Under department rules, schools are not entitled to have a substitute on the first day of a teacher's uncertified leave.
They also can't always amalgamate classes as there are restrictions on the number of children that can be in a class at one time.
According to Ms Barron, it is more difficult for small schools that don't have numerous classrooms to divide the children between when a teacher is out.
"Let's just imagine you were in a four-teacher school, and you've got 120 children there, you've got 30 in each room, you are then trying to split 30 children across the other three rooms."
"Many of us are in smaller classrooms than we should be."
Special education teachers
Special education teachers are also sometimes used in lieu of those absent - something schools are "reluctant" to do.
"[Children with additional needs] don't get their needs met," she said.
Listen back to the full conversation here.
Main image shows a classroom in a newly built school. Simon Turner/Alamy