Schools have been putting contingency arrangements in place in advance of next Tuesday's one-day strike by members of the Teachers Union of Ireland.
The action is expected to close hundreds of post-primary schools, and cause disruption in some colleges of further or higher education.
Up to 5,000 students who are studying the Leaving Certificate Applied programme have assessments that are due to take place next week.
Examiners from the State Examinations Commission have been re-jigging timetables to compensate for the anticipated closure on Tuesday of many schools offering the LCA programme.
Many schools have also been forced to alter timetables for mock Leaving and Junior Certificate Exams that are scheduled to take place next week.
At least half of the country’s more than 700 second level schools are expected to close on Tuesday, affecting upwards of 170,000 students.
The vast majority of the 343 schools in the Education and Training Board (ETB), and Community and Comprehensive sectors will close. These schools traditionally have teaching bodies comprised mostly of TUI members.
However many other schools, where the ASTI trade union is dominant in staff rooms, are also likely to close. This is because ASTI members will not take on any work normally done by a TUI colleague on the day. So any school with even a small number of teachers who belong to the TUI is at risk of closure on Tuesday.
For instance one midlands school with just seven Teachers Union of Ireland members on its staff has confirmed to RTÉ News that it is closing on Tuesday. Another nearby school that is predominantly ASTI will also close.
Another school where 17 out of its 50 teachers are TUI members has told RTÉ News that it will close. "Our Board of Management has accepted and decided we cannot discharge our duty of care", the school principal has said. The school has also "rescheduled slightly" its mock exams to allow for the closure.
This principal said: "The one day strike won’t have massive implications. However any further action would of course cause me concern in relation to the practicalities of the exams, practicals, orals etc."
The National Parents Council Post Primary has criticised the planned strike, saying that "emphatically no industrial action should take place during classroom hours or disrupt lesson time for pupils".
Teachers Union of Ireland members are striking as part of their campaign to fight pay discrepancies which see teachers employed after January 2011 earning less than colleagues who entered the profession prior to that date.
The union said while it regretted any inconvenience caused to students, "our survey findings released earlier this week show the severe damage that pay discrimination is already inflicting on the service to students in terms of a teacher supply crisis across the breadth of subjects, with over half of schools advertising positions for which nobody applied."
The ASTI has also decided to ballot its members on industrial action over unequal pay "to be taken in conjunction with one or both of the other teacher unions".