The principal of St Peter and Paul's school in Baldoyle, Dublin, says teachers face an almost impossible task in trying to teach overcrowded classes.
Class size is a huge issue in the school. There are 36 pupils in first class and 32 in fourth class.
The problem extends to the infants' classes, where there are 29 pupils in junior infants and 28 in senior infants.
The principal, Donal O'Donoghue, says teachers are doing their very best to meet the individual needs of their pupils, but they are trying to do the impossible with these numbers.
He says the increasing number of non-nationals and the growing curriculum demands make it imperative that class sizes are reduced without delay.
The Republic has the second most crowded classrooms in Europe. According to the INTO, more than 100,000 pupils are in classes of 30 or more across the State.
The INTO says, for example, that 37 per cent of primary school pupils in north Dublin are being taught in classes of 30 or more.
In its pre-Budget submission recently, the INTO said 34 per cent of pupils in "the Minister's own constituency" of Dún Laoghaire-Rathdown were in classes of more than 30. The pattern was broadly similar, it said, in Kildare and Meath.
Its general secretary said: "We have a new, modern curriculum based on worldwide best practice. Teachers are expected to organise individual or personalised learning, co-operative learning, group teaching, more use of resource materials to facilitate activity-based learning and the increase in the use of ICTs.
"But without class-size reductions we are only scratching at the surface in terms of delivery - the full potential of the primary school curriculum cannot be achieved."
