Secondary schools are struggling more than ever to hire good teachers, a teacher's union says.
The Post Primary Teachers Association said its annual staffing survey found schools could not fill 27 percent of their advertised vacancies and 56 percent of principals had to employ untrained or unqualified teachers because they could not find trained and qualified staff.
It said 125 principals responded to the survey in March and their responses showed New Zealand-trained teachers were in short supply.
"The normal experience of principals was not having a choice in selecting applicants from New Zealand for classroom jobs because there were either none (40 percent) or only one (24 percent)."
It said 56 percent of the responding principals said they had teachers teaching subjects they were not qualified to teach, the highest figure the survey had recorded.
The survey also found 30 percent of responding schools had cancelled courses or transferred them to distance learning because they did not have enough qualified teachers.
PPTA president Chris Abercrombie said the results showed the secondary teacher shortage was affecting schools throughout the country.
"The shortage is affecting schools in big cities just as much as in the traditionally harder to staff rural areas. The number of New Zealand-trained teachers applying for classroom teaching jobs has never been lower," he said.
Abercrombie said the high number of teachers working outside their subject specialist area was especially worrying.
"This means that more and more young people risk missing out on the deep grounding in subjects that they should be getting. Students need teachers who know their subject area inside out, are passionate about it and can stretch students' knowledge and skills."
The government has put foreign secondary teachers into a fast-track category for New Zealand residence.
Abercrombie said overseas teachers were not a long-term solution to the shortage. He said the country needed a constant and abundant supply of New Zealand-trained and qualified secondary teachers.