Teachers will walk off the job during Year 12 exams across South Australia if the state government fails to provide an improved pay offer.
Members of the Australian Education Union on Thursday voted 83 per cent in favour of taking strike action on Thursday, November 9.
The union is seeking an increase on the government's offer of a three per cent pay increase and a reduction in instructional hours to ease workloads.
"Whether we strike is now a matter for the Malinauskas government who have the power to make an offer which demonstrates a commitment to public education in South Australia," SA branch president Andrew Gohl said.
"While salary is important, we've said consistently that this is not just about pay, but also securing a set of working conditions that ensure our educators can provide the very best for their students.
"Every day, thousands of South Australian students are going without a consistent teacher. It is a crisis affecting schools and preschools right across our state, requiring urgent and significant action."
Education minister Blair Boyer called the outcome of the vote disappointing and said both parties had been negotiating positively.
"I've said from the outset, I didn't think that industrial action was needed," he told ABC Radio on Friday.
"These things take some time, but we're talking about more than a $1.3 billion expenditure of public monies over the life of the agreement."
Exams will go ahead for Year 12 students, but the minister was worried about the inconvenience to students and families.
"Some students who have been through three years of COVID, they have probably had a more disrupted high school experience than anyone - I've heard some people say - since the Second World War," Mr Boyer said.
"To have the spectre of industrial action, or not knowing what is going to look like on Thursday when they roll up, I think is something we could well and truly do without."
The union says the government has until Monday to provide a satisfactory offer to avert the strike.
"This is about priorities, and when the premier can find $2 billion for submarines and $450 million for a university merger, we should not accept that public education and our students aren't worth the same investment," Mr Gohl said.
Thousands of teachers walked off the job in September, shutting or affecting teaching at hundreds of public schools across the state.
The union called off a follow-up strike later that month after it appeared the parties were closer to reaching an agreement.