NSW Teachers Federation head Angelo Gavrielatos warns that "thousands upon thousands" of children are missing out on their education every day as the teacher shortage crisis worsens.
A new report says almost 60 per cent of educators plan to leave the sector in the next five years.
"The last thing that we can afford is to be losing the teachers we have got," Gavrielatos told Today.
READ MORE: 'Another possible flood event' coming, BoM warns
"The government is letting down a whole generation of kids, and future generations are potentially being let down as well."
Every day, he said, thousands of students were reporting that they had their classes merged, forgotten, or cancelled, as schools scrambled to plug teaching gaps.
Gavrielatos said while the pandemic had exacerbated the issue, the teacher crisis predated COVID-19 by years.
He said that teachers had not had their working conditions changed for, in some cases, seventy years.
READ MORE: CCTV released as investigation into Sydney murder continues
"There has been no change in teacher planning and preparation time since the 1950s for secondary teachers and 1980s for primary school teachers," he said.
"They have two hours a week in the entire week for planning and preparation. That's it."
In the same time, he pointed out, many efforts had been made to address changing understanding of student and parental needs.
"The government has got thousands of pages of research and analysis that says the two most important factors here are unsustainable workloads and uncompetitive pay," Gavrielatos said.
"Yet the government appears to be wanting to do everything else other than dealing with the root cause of the issue."
Teachers have gone on several strikes in recent months, trying to draw attention to the crisis.
