A troubled Rotherham special school is to be hit by two days of industrial action on Wednesday and Friday this week.
Support staff are striking at Abbey School at Kimberworth in a long-running dispute over redundancies and poor pupil behaviour.
Workers say behaviour has deteriorated since a number of experienced teachers decided to take redundancy offers.
Union GMB claims school managers and the local authority are refusing to negotiate on recruitment issues.
Rotherham Council says it is committed to doing all it can to provide pupils with a first class education.
Lee Simpson, GMB convenor, said school managers were now blaming staff for the poor behaviour displayed by pupils, refusing any responsibility.