Classes have been halted across Victoria as thousands of striking public school teachers, principals and education support staff prepare to descend on state parliament for a rally over pay and conditions.

According to the Australian Education Union’s Victorian president, Justin Mullaly, up to 500 schools would either be closed or “significantly affected” as a result of the first strike in the state’s public school system in more than 13 years.

“The advice to parents is that it’s best not to send your child to school,” Mullaly told reporters on Monday.

There were reports on Tuesday morning that some Melbourne schools had seen few children arrive. This was despite Victoria’s education department previously insisting that schools would remain open.

The Fair Work Commission approved the action two weeks ago, after 98% of AEU members voted to strike for 24 hours over what they say is low pay and excessive workloads.

An education department spokesperson conceded some schools won’t be able to support all children, despite remaining open.

“While all schools are expected to be open tomorrow, many schools will only be able to provide supervision for a limited number of students,” a department spokesperson said on Monday.

“Schools will communicate any changes to school programs directly to parents and carers.”

A significant cohort of the 30,000 AEU members on strike were expected to march from Victorian Trades Hall to parliament for a rally on Tuesday afternoon.

Some principals, who were also planning to participate in the rally, have told their school communities that supervision would only be available for the children of emergency workers.

The Australian Council of Trade Unions’ secretary, Sally McManus, said Victorian public school teachers sacrificed their pay during Covid lockdowns and opted for a small increase before inflation took off.

“There’s a real depth of anger amongst Victorian teachers,” she told ABC Radio on Tuesday.

“They’re now the lowest-paid teachers in the country.”

The AEU went into EBA negotiations about eight months ago, seeking a 35% pay rise over four years, smaller class sizes and improved mental health and classroom support.

The government responded with a 18.5% pay offer – only after the union moved to strike.

This offer included an 8% pay rise for teachers and 4% for education staff to come into effect in April, followed by a 3% rise for each of the following three years, as well as a 1.5% overtime allowance.

The Victorian premier, Jacinta Allan, had urged the strike not to go ahead on Monday.

For those students in the Catholic and independent sector, schools were operating as normal, though the union representing their teachers issued a statement in support of colleagues in the public system.

“Salaries in Victorian education have fallen significantly below those in other states, and we fully back the AEU campaign for fair pay and urgent improvements to workload and staff wellbeing,” the Independent Education Union’s general secretary, David Brear, said in a statement published by the Age.

The IEU was also negotiating a new deal for staff in Catholic schools, and has been pursuing a case in the Fair Work Commission.

– with Australian Associated Press