Teaching isn't the stable profession it once was, a report has found, with one in five NSW state school teachers now employed on short-term contacts.
A study of 18,000 public school teachers, who are members of the NSW Teachers Federation, explored the workload reports of teachers in temporary employment.
The research was drawn from a broader study in 2018.
The report found many teachers on temporary contracts felt they needed to work harder than the permanent staff in order to "prove themselves" to the school executive.
"There is a huge expectation that teachers put their hand up for extra roles ... which adds to the pressure teachers (particularly temp teachers as we do more) feel," one teacher said.
Lead author of the report, Dr Meghan Stacey from the UNSW School of Education, told AAP the data showed teachers in temporary employment were doing a similar amount of work to teachers in permanent roles.
"But as temporary employees they don't have the same type of security," she said.
Fixed-term contracts were introduced about 20 years ago and were a growing category of employment for teachers in NSW public schools.
"Temporary teaching work is not like casual work - the hours and demands are considerably higher," Dr Stacey said.
"There's a frustration because they're essentially doing the same work as permanent teachers, just without any security."
Another author, Associate Professor Rachel Wilson from Sydney University, said the situation required "serious policy attention".
"It would be really good if studies like this weren't needed, and instead there was a monitoring program in place," she said.
The NSW Teachers Federation said the reliance on temporary teachers was making teaching a less attractive profession.
Deputy president Henry Rajendra called on the government to fully staff public schools with appropriately trained teachers.
"This staffing crisis needs urgent attention from the Berejiklian government," he said.
"Schools cannot be held responsible for finding non-existent staff."
The NSW Department of Education has been approached for comment.
Australian Associated Press