Headteachers have warned parents that primary schools in parts of County Down are facing "financial disaster".
Fifteen principals from schools in Comber and Newtownards have written a joint letter urging parents to contact the authorities over school budgets.
The letter said spending cuts will mean fewer teachers and resources, larger classes and worse education outcomes.
It urged parents to contact MLAs, the Department of Education and the Education Authority about the issue.
"We all strongly believe that parents and guardians should know of the current and future financial difficulties that face all schools in the area," they wrote.
However, a spokesperson for the Department of Education said that "providing financial assistance to schools" had been one of the Education Minister Peter Weir's priorities.
The principals' letter said that each school represented was facing a "crisis, no matter how strong the enrolment or how big or small the school".
"In the past five years the money given to school per child has only risen by 0.9% whilst costs have risen by approximately 14.5%," it said.
"This dire financial situation is not being addressed by either the Department of Education or the Education Authority.
"The impact is real, urgent and disastrous."
Chris Logan, principal of Comber Primary School, said parents had been very supportive of the letter.
"They understand that all the schools on this list are working incredibly hard for their pupils all the time and all they want is good outcomes for their pupils," he said.
"All we're asking is for awareness to be raised, that parents come alongside schools and support them and make sure that we protect provision."
Education minister Peter Weir said that, while he did not accept everything in the letter, schools were facing "very major pressures".
"Within education we need somewhere in the region of about £200m to £240m cumulatively over the next three years in terms of resource budget into schools," he said.
"That is what is needed to plug the gap, that is the major challenge that is going to be there for the executive and people need to face up to that.
"So, from that point of view, the concerns that have been raised, while it may be a little bit exaggerated in terms of the scale within the letter, they are very genuine concerns and it does need additional funding to be found within the education system.
"Additionally, I also think there is a need for a level of reform within the education system."