Hundreds of secondary schools will be forced to close on seven days over the next two months as teachers strike over a long-running pay row.
The Association of Secondary Teachers' of Ireland (ASTI) said its members would stage a series of one day stoppages culmintaing in a two day walk-out in December.
The union announced the strike days for Thursday October 27, then in November on Tuesday 8, Wednesday 16, Thursday 24, Tuesday 29 and consecutive days in December on Tuesday 6 and Wednesday 7.
Some 80% of ASTI members voted for the action over lower pay rates for newly qualified staff.
President Ed Byrne said: "Recently qualified teachers spend five to six years training, including obtaining the required master's qualification for teaching at second-level.
"They are then expected to teach alongside colleagues who have completely different pay arrangements for their entire careers.
"The sense of injustice amongst all teachers is palpable. ASTI members are committed to achieving equal pay for equal work for all teachers."
The ASTI is Ireland's largest second-level teachers' union with 17,500 members in more than 520 schools.
Emer Kelly, an English teacher in the Royal and Prior Comprehensive in Raphoe, Co Donegal.
"It's unfair. My colleague and I do exactly the same job teaching in the English department and she gets paid less than me. That is not right," she said.
"If the salary was deemed too low a rate to live on when I began in 2007 how is it liveable now?"
About a quarter of the teaching staff in the Royal and Prior are on the lower salary scale.
Ms Kelly said the disparity does not dominate relations between younger and older teaching staff but there are concerns resentment will set in over younger staff feeling they need to take on more additional unpaid roles in order to further their careers and get more secure or permanent contracts.
Along side the strike days ASTI members will also withdraw from supervision and substitution work from Monday November 7.
Education Minister Richard Bruton said there is cash on the table to resolve the dispute over the Lansdowne Road Agreement and the gradual restoration of pay.
Mr Byrne said: "ASTI members' democratic decision to reject the agreement was met with an extreme and hostile reaction by the Government, including targeting young teachers' access to job security.
"Teachers are reluctant to take industrial action or to interrupt the running of schools in anyway. However, we have flagged our serious issues well in advance and remain available and committed to a resolution through talks without pre-conditions."
Mr Bruton said the strike means severe disruption to students and parents is inevitable.
He also said it was regrettable that the union was not cooperating with contingency plans to give schools enough time to have replacement staff for supervision and substitution duties go through Garda vetting.
"The issues of concern to ASTI members can only be resolved through dialogue," a spokesman for the minister said.
"The minister hopes that the union can now engage in constructive dialogue with the department.
"The minister emphasised that he has not and will not be setting any pre-conditions to dialogue taking place.
"This has previously been made clear to the ASTI leadership."