Victorian public school teachers, principals and other education staff will not show up for work on Tuesday over a pay dispute, while teachers in Tasmania will also strike.
About a third of the 30,000-strong unionised workforce are expected to march from Victorian Trades Hall to state parliament for a rally on the front steps.
Schools will remain open across the state, but many parents have been told classes won't run and to keep their children home if possible.
A school in Melbourne's outer east recommended parents make alternative arrangements for their children, while only four of 34 classes were slated to run at a nearby primary school.
The Department of Education did not provide details on how many schools would operate at reduced capacity on Tuesday, but confirmed it was working to limit disruption.
"Whilst all schools are expected to be open ... many schools will only be able to provide supervision for a limited number of students," the department said.
"Schools will communicate any changes to school programs directly to parents and carers."
The 24-hour teachers strike is Victoria's first in more than 13 years and comes eight months out from the state election.
Premier Jacinta Allan pleaded for the Victorian branch of the Australian Education Union to cancel the action and return to the negotiating table to prevent disruption.
But the union told AAP the strike action would go ahead as planned.
"Our students and their families do not deserve to have teachers, principals, and education support staff that are underpaid and undervalued," Victorian branch president Justin Mullaly said.
"The premier and the education minister need to act immediately on this."
The union threatened to escalate the industrial campaign further, if necessary.
A Victorian parliamentary inquiry is investigating Labor's decision to delay increasing school funding to 75 per cent of the Schooling Resource Standard until 2031.
The union argues this effectively equates to a $2.4 billion cut in funding from what was previously committed.
Deputy Liberal leader David Southwick accused the state government of being more focused on the demands of the CFMEU than the teachers' union.
"They (teachers) deserve to be paid more," he said.
Victoria's budget is under strain from mounting debt and underlying economic assumptions could be tested by a global inflation shock following the outbreak of war in the Middle East.
Public schools will also close in Tasmania over three days as teachers strike in their battle for improved pay and conditions.
Stop-work action will begin in the state's northwest on Tuesday, followed by the north on Wednesday and the south including Hobart on Thursday.
Tasmania and Queensland have offered teachers an eight per cent pay rise, below the 13 per cent offer made to those in the Catholic system.
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