The country's largest teachers' union says strike action could be on the cards over the Government's Junior Cert reform.
The ASTI says its members will be balloted next month over the plans, "and if necessary could push it to the limit".
The reforms, which will be phased in from September, will see a move away from a single, State exam towards continuous assessment, with projects and exams graded by the students' own teachers.
Education Minister Jan O'Sullivan is due to meet the teachers' unions next month to hear their concerns in a bid to avoid the action.
ASTI General Secretary Pat King says strike action cannot be ruled out.
He said: "We're having a ballot in the next couple of weeks, it could result in strike action, but that's down the road
"We are currently refusing to cooperate with some elements of the new Junior Cycle programme.
"We are concerned, if we don’t make progress in the very near future, it could become much more serious."