Teaching unions say more investment is needed in secondary schools to meet the growing number of students.
The Department of Education is predicting numbers will rise sharply at second level over the next four years.
General secretary of the Teachers Union of Ireland, Michael Gillespie, says students can’t be taught in overcrowded classrooms.
"Every problem we have in Ireland - if we ever solve it - will be solved by the people we're teaching."
Mr Gillespie said we have to invest in our students for our future.
The union head said this is something they've been warning the Government about for years.
"Of the 36 OECD countries, we are spending the lowest."
"I think we're on 1.1% as opposed to 1.9% on average, so we've a lower investment in second levels."
Concerns For Primary Schools As Numbers To Drop By 20%
Meanwhile, at primary level there are concerns about the future of small rural schools.
The Department of Education is predicting numbers will fall by 20% over the next 15 years, as women are having fewer children.
This will lead to smaller classrooms but there are concerns whether small rural schools could stay open.
John Boyle from the Irish National Teachers Organisation says these schools provide the same quality as the larger ones.
Mr Boyle attended a two teacher school and was a principle in 40 teacher school for twenty years.
"The quality of education in those smaller schools are just as good."
