Teachers are juggling more complexity in the classroom than ever but lesson preparation hours have not changed in decades.
A survey of almost 20,000 NSW teachers' findings that only 15 per cent had enough time for lesson planning will underpin a union push for extra hours of paid out-of-classroom prep time.
NSW Teachers Federation president Henry Rajendra said it was not only teachers sounding the alarm.
"Parents know this is a serious problem and want it fixed so that their kids get a teacher who has had the time to plan for the needs of their students," he said.
Preparation hours for the state's primary teachers have not increased since the 1980s and there has been no change for secondary teachers since the 1950s.
That's despite rapid advances in technology, policy and curriculum changes, and more students with disabilities making modern classrooms more complex to manage, according to a 2021 Gallup Inquiry.
Chaired by former WA Premier Dr Geoff Gallop, the inquiry recommended boosting the time teachers have to prepare lessons and collaborate with colleagues by two hours.
NSW Minister for Education and Early Learning Prue Car said significantly more teachers would be needed to provide any increase in preparation time.
"For the Department of Education to provide widespread release time, it would require significantly more teachers and create vacancies just as the sector recovers from the chronic teacher shortage that exploded under the Liberals and Nationals' wages cap," she said in a statement to AAP.
Ms Car said her government had made progress in raising teacher pay, lightening staff workloads and addressing workforce shortages.
"We know there is more work to do, and we'll continue to listen to our hard-working, dedicated teachers as we support them in doing what they do best - teaching kids in the classroom," she said.
Mr Rajendra applauded the "meaningful progress" on teacher pay and workforce shortages, currently at their lowest levels in more than a decade.
"Now it's time to finish the job and commit to the additional preparation time teachers desperately need," he said.
