The Taoiseach insisted the number of teachers in the second-level system would increase from 25,307 to just under 26,000 for the academic year beginning in September.
Mr Ahern was replying to the Fine Gael leader, Mr Enda Kenny, who challenged him on "a schizophrenic decision of the Government that 300 teaching posts are to be cut in the area of physical sciences".
He said the number of pupils in the second-level system had decreased by more than 32,000 in recent years, from 371,000 in 1996-97 to 339,000 in the academic year just gone.
He added that the pupil-teacher ratio at second-level had fallen from 16:1 to 14:1 since 1996-97, and the projected ratio for the current year was 13.6:1. More than 1,200 additional teaching posts had been created in the second-level sector in the past four years.
The curriculum issue could not be viewed in isolation from the overall school needs and staffing allocations.
"For the first time this year, an independent appeals committee was established to consider appeals from schools regarding their allocations for curriculum needs.
"A total of 143 second-level schools from almost 750 applications have submitted appeals and the committee has granted 65 posts. These are the facts and figures."
Mr Kenny remarked: "A person would want a master's degree in calculus to figure out what that means."
Mr Ahern replied: "It means there will be more teachers this year than last year. It is simple."
Mr Kenny pressed Mr Ahern to say if 300 concessionary teaching posts were being axed in September. Students of minority subjects were "being condemned by a tunnel of darkness".
Mr Ahern said for the forthcoming school year the number of whole-time equivalent teaching posts being made available for curricular concessions was 699, a reduction from 871 posts in the current school year.
But the figures for staffing allocations were up, the number of pupils was down and the pupil-teacher ratio was down.
