Strike action at Movilla High School in Newtownards is to continue, the NASUWT teachers' union said today.
The union today rejected a route out of the dispute with the South Eastern Education and Library Board (SEELB).
The strike is in its ninth day and centres on the education of a pupil who teachers insist requires specialist care.
After teachers held a meeting this morning, the union revealed its industrial action was to continue, but said it will withdraw one of three proposals for the education of the 15-year-old its members had put forward.
The union has accepted the pupil will not be taught by specialists in isolation at the school.
The union said its remaining recommendations for meeting the boy's particular needs were reasonable and claimed the Board was refusing to enter real discussions.
Teachers' representatives said they were asked to agree to an independent assessor's recommendations to end the dispute, but without sight of the report on which the relevant findings were to be based.
In a statement the union said: "We believe that due to our employer's absolute refusal to engage in meaningful negotiations we have no option but to continue our strike action until such time as the dispute can be settled on a basis which provides for the particular pupil's special needs to be met and for a safe learning environment for students and staff at Movilla High School."
The strike began on October 13 after teachers' pay was docked for refusing to teach the pupil who they claim assaulted one of the staff.
The 15-year-old is to appear before a juvenile court next month in connection with the allegation.