Tasmanian parents are being urged to make alternative arrangements for their children on Friday, with teachers set to walk off the job for the second time in less than two months.
The Australian Education Union (AEU) has called a statewide strike for December 12, with many public schools expected to close.
The union says members are increasingly frustrated by stalled enterprise bargaining negotiations with the state government.
It says support staff are facing yet another Christmas without a pay rise, along with several weeks of unpaid leave over the summer break.
“Educator workloads are no longer safe, for students or for workers,” the union said.

Rising school violence, heavy workloads and growing staff burnout are also driving the planned industrial action.
The strike follows stop-work meetings in October, which saw schools delay opening until 11am across three consecutive days.
Education Minister Jo Palmer said schools will be closed until 12pm on Friday.
“Schools have worked hard to ensure pre-planned end-of-year activities that cannot be rescheduled still go ahead,” she said.
“Schools will remain open for these activities, where possible, ensuring students and communities can continue to participate in these highly valued events.”

“Schools will communicate directly with families regarding their specific arrangements.”
Palmer said the union is encouraged to stay at the negotiating table.
The final day for Tasmanian public school students is December 18.