The ASTI is to introduce a policy establishing a maximum second-level class size of 20 for all subjects from the start of the 2008 school year, after delegates at its annual convention voted unanimously in favour of the move.
Delegates were presented with details of a recent survey that found that 64 per cent of third-year students are taught in overcrowded classes of 25 students or more, with 16 per cent taught in classes of 30 students or more.
The ASTI estimates that this equates to more than 100,000 students being taught in classes of 25 or more, while more than 25,000 students are taught in classes of 30 or more.
In his presidential address yesterday evening, Michael Freeley said large class size is the cause of great stress to teachers and is unfair to students.
"Large class size is also adding to our discipline problems. The bureaucratic burden being experienced by teachers must be minimised so that more quality time can be devoted to what we all want to do and love to do, that is teaching." He pointed out that the overwhelmingly majority of teachers have never received any in-service training in relation to the welcome mainstreaming of education.
It was "immoral" to think that the recent case of autistic schoolboy Seán Ó Cúanacháin had to run in the High Court for 68 days at an estimated cost of €5 million, he added.
Mr Freeley's comments on class size were echoed by a number of delegates, with one suggesting that the ASTI should take out billboard advertisements to get across the message of the impact of class sizes on students.
Another delegate, former national organiser Noel Buckley, also said there was a need for the media to be more critical of the Government's claim that there is one teacher for every 13 students at second level.
He pointed out that this included those teachers, such as school principals and programme co-ordinators, who were tied up in administrative work, and were "not in the classroom."
Elsewhere, the conference heard claims that the controversial Whole School Evaluation (WSE) process has led schools to "put on a performance" for inspectors having been notified in advance of their visit. Maire Ní Chiarba from north Cork said she was aware of some schools cancelling mock exams and another principal who had cancelled all matches and games while the evaluation was taking place.
"What's the point in having three weeks notice if it's used to put on a performance?" she asked. "The merits of WSE have to be looked at in greater detail."