The Australian Education Union (AEU) is calling on the Victorian government to address the workload of teaching staff following a "concerning" report.
The union conducted a survey of more than 10,000 Victorian teaching staff including principals and support staff that revealed 84 per cent think their school is under-resourced and that many were working an average of 15 hours of unpaid overtime a week.
Michelle Butters, who has been a teacher for about seven years, said the workload was taking a toll on her.
"A standard workweek is 38 hours, but most teachers are working over 50 hours," Ms Butters said.
"It takes time away from me and my partner."
AEU Secondary vice-president Marino D'Ortenzio said the results from the survey were extremely concerning.
"The simple truth is that many of our members are working after hours during the week and also working on weekends in order to get their work done," Mr D'Ortenzio said.
According to the survey, 85 per cent of staff said their work-related stress had increased significantly in the last 12 months.
"Students are emailing us at all times and whilst we don't have to respond to those emails, it's actually really difficult to ignore your students," Ms Butters said.
Mr D'Ortenzio said COVID-19 had impacted teachers but stressed that workload issues predated the pandemic.
"There has been an intensity of work and a workload problem for a number of years now," he said.
"The message right across the state is: The amount of work that's been asked of our members just cannot be done in the time that they're paid to do the work."
Concerns have also been raised about how the workload impacts students.
Ms Butters said teachers were not always able to give students their undivided attention because of the amount of other tasks they had to perform.
"We'll always put the students first … but there are some students who do feel like they're falling through the cracks," she said.
"When we're spending so much time working on things behind the scenes it makes it harder to spend time planning for your next lesson.
Mr D'Ortenzio said rural and regional areas already struggling to attract teachers could find themselves more disadvantaged in years to come.
"It's already harder to staff certain subject areas [in rural and regional areas]," he said.
"We know it's already harder to fill some vacancies.
Mr D'Ortenzio said burnout was already driving people out of the profession.
"We've had pretty concerning reports around staff thinking they might not be in the system beyond five or 10 years, which is really concerning, to lose that expertise," he said.
Ms Butters said several colleagues and a number of people she went to teaching school with had already given up the job.
She said it was also difficult for new graduates who felt additional pressure to put in the extra working hours.
"They have job insecurity because they're on a contract," Ms Butters said.
"They feel like they have to put in the long hours, otherwise their contract may not change over to a full-time position."
She urged teachers to stick to the profession but agreed that something needed to change.
"I don't even know where to start with the solution," she said.
A spokesman from the Department of Education said the government is continuing to give teachers extra resources and training but said it would not comment further on the matter.
“Teacher work is a subject of the current enterprise agreement negotiations in respect of a new industrial agreement to cover the Victorian Government Teaching Service," the spokesman said.
“As the parties have agreed confidentiality protocols throughout the bargaining period, it would be inappropriate to comment on matters which are the subject of negotiations at this time.”