Refusing to cover colleagues' absences, invigilating exams or analysing exam results - NI teachers taking part in escalating industrial action in a row over pay.

Teachers in Northern Ireland are taking part in escalating industrial action in a row over pay. Union members are following instructions not to cover absences, invigilating exams and analysing exam results. After school activities like sports and drama that have been "imposed" on teachers may also be affected. Stephen spoke to Justin McCamphill from teaching union NASUWT.