The union representing primary school teachers says a quarter of children are in supersize classes.
At the moment, the Department of Education provides a teacher for every 27 pupils, however, the Irish National Teachers Organisation says more than 130,000 children are in classes of 30 or more.
The INTO is calling on the next government to reduce class sizes to 22 over the next 5 years.
John Boyle is the Vice President of the INTO, and Principal of St. Colmcille’s National School Knocklyon in Dublin.
He says some junior infant pupils in his school are in classes of 34, "in our school last year for instance, I had hoped that we'd have eight classes of 27.
"Suddenly I found myself with 27 children with no teacher because I was a few pupils under the figure for appointing a new teacher. I had to divide those children among the remaining teachers," Boyle said.