It was announced there would be a half-day strike and action short of a strike this month
Members of the Irish National Teachers' Organisation are starting industrial action over a pay dispute.
Before Christmas, it was reported the union would stage a half-day strike, and action short of a strike this month.
The group won't co-operate in school inspections by the Education and Training Inspectorate at this point in time.
The union has seven thousand members across Northern Ireland.