The Government is being accused of failing to provide adequate levels of school funding and to make proper provisions for the anticipated rise in pupil numbers over the coming years.
Eight hundred new teachers are due to be recruited next year, but teachers' unions and opposition parties say this won't make any significant difference to class sizes in the long run.
They predict that the number of pupils will increase by more than 20% over the next 10 years, which will outstrip the rising teacher numbers.
Labour TD Jan O'Sullivan says schools are also not being provided with enough funding in the forthcoming budget to meet basic costs like electricity.
"In real terms, schools are still going to have to ask parents to cough up and pay money for the basic needs of schools and that isn't the way it should be," she says.