Parents will have to plan ahead as thousands of teachers across the Illawarra are anticipated to go on strike for 24 hours on Tuesday.
The Teachers Federation president said the state-wide industrial action by public school teachers would proceed next week despite the NSW Industrial Relations Commission ordering the union to refrain from striking over its wage claim.
Illawarra Teachers Association president and local primary school teacher Elizabeth Scott said many of her colleagues felt the public service cap on wages had meant they had been "left behind".
She said there was a need to improve the status of the profession and to attract new teachers and the way to do that was through a competitive salary and better working conditions.
"Our workloads are unmanageable and we have a lot of students with complex issues, mental health concerns and teachers have dealt with two lockdowns," Ms Scott said.
"We are facing a massive teacher shortage in the next few years. We need to attract young teachers and for them to stay in the profession, especially once older teachers retire."
Ms Scott said the biggest issue facing the Illawarra was a lack of casual relief staff to replace teachers on a day-to-day basis.
"Last week I had three classes that I could not get a casual teacher to cover," she said. "That meant we had to split classes up into others which affects the programs planned. It is not ideal.
"That happens in my school at least once a week and it is happening across the Illawarra."
Ms Scott said teachers had to complete a large amount of administrative tasks such as data collection and risk and accountability procedures which was taking time away from preparing and teaching lessons.
She said the public school sector also did the "heavy lifting" when teaching children with disabilities.
She added the pandemic lockdowns had been particularly difficult for teachers given many were still required to go to the school a few days a week and manage and support children and their families.
Ms Scott said some schools were likely to be "non-operational" or have skeleton staff on Tuesday.
"This is not sudden action," she said. "We have been presenting our case for more than a year yet the government is sticking to the public service cap and not following their own department's advice.
"What more can we do? We are reaching a crisis point."
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