Almost 3000 unfilled full-time teaching jobs are on offer in NSW which the union and Labor both see as a failure of Dominic Perrottet's government.
Newly released government figures show there were 2963 vacant positions at the end of October - a massive increase from 1148 vacancies in May 2021.
NSW Teachers Federation president Angelo Gavrielatos said the number of vacant teaching positions represented "a classroom crisis".
"These numbers reflect the utter failure of the Perrottet government to address the real causes of the teacher shortages which are unsustainable workloads and uncompetitive salaries," he said on Sunday.
He said the chronic shortage will worsen with rising enrolments, an ageing workforce and 30 per cent decline in the number of people studying to become a teacher
Mr Gavrielatos said uncompetitive salaries against the backdrop of rising inflation were "a major reason why the number of people studying to become a teacher has plummeted".
Labor said it would solve the crisis by slashing workloads with an expanded recruitment campaign to hire 10,000 permanent teachers statewide.
"Every day, parents, students and teachers experience the real-world impact of this shortage, through merged or cancelled classes and students being left with minimal supervision," Opposition Leader Chris Minns said.
He also committed to building a public high school in southwest Sydney to keep up with the growing population if elected.
Mr Minns said the NSW government was under-delivering on 113 school infrastructure projects, spending $1.26 billion less than promised in the 2021-22 budget.