Dubbo teachers say they're facing violence, burnout and unmanageable classroom sizes due to a chronic shortage of staff.

The latest government data shows 44 teaching roles remain empty in Dubbo, and over 30 per cent of the workforce is on temporary contracts.

Dubbo teacher Brayden Holland said teachers were often asked to teach two or three merged classes outside at once due to the staff shortages.

The high school teacher said it was impossible to control a classroom under such conditions, resulting in "no learning", bad behaviour, and outbreaks of violence.

Mr Holland said he was assaulted in March while trying to intervene in a fight between two students who had been merged together into one classroom.