The Education Ministry has begun investigating whether sexism has suppressed teachers' pay.
The pay equity investigation covers about 90,000 school and early childhood teachers and principals and follows claims lodged by the Educational Institute and the Post Primary Teachers Association in 2020.
The unions said teaching had been undervalued right across the education sector because the education and care of children was historically viewed as women's work.
Ministry figures indicated 64 percent of secondary teachers, 85 percent of primary teachers and 97 percent of early childhood teachers were women and, depending on qualifications and experience, their base pay scale ranged from $51,358 to $90,000 a year.
Early childhood teacher Mel Burgess helped the Educational Institute lodge its claim in 2020 and said she realised there was an equity gap when she graduated from teacher education.
"I held the pay scale that I could expect to be earning once graduating side-by-side with the fees that I had just clocked up and I realised it was a huge disparity in that and at that moment wondered if it was worth it.
"At the same time I knew of somebody who was graduating, same length of degree as me, going into IT and their starting salary was going to be $20,000 more than what I could expect and that was the moment I knew that thing were pretty unfair," she said.
Burgess said she hoped teachers would get the sort of settlement other education staff had won in recent pay equity decisions.
"So for people like support staff and teacher aides, librarians and science techs, they've seen some really big jumps of 20 to 30 percent and I would love to see something similar to that. I think that's what we deserve," she said.
"All the professions that are undervalued are those ones that are predominantly done by women or are relying on what they like to call soft skills, jobs that require empathy or understanding how people work or human communication, all those kinds of things.
"I think that's what I would like to see addressed because that kind of work is extremely challenging to do well and people underestimate the skill and the expertise that's needed," Burgess said.
The OECD's Education at a Glance publication said New Zealand primary teachers earned 94 percent of what workers with similar tertiary qualifications earned in other professions, but secondary teachers earned the same as those with similar qualifications.
Louise Ryan from the Post Primary Teachers' Association said secondary teachers' pay used to be one-and-a-half times the average salary but by 2020 that had declined to one-and-a-quarter as the secondary teaching workforce became more feminised.
"Early 1990s probably more than half of the secondary teaching workforce would be female, and at the moment, we would say that about 70 percent of secondary teachers are female and over the past 20 years we've seen that downward trend in secondary teachers' base pay relative to the average wage and we do believe that this is connected to that increasing feminisation," she said.
Ryan said teachers' pay was determined through collective bargaining with the Education Ministry and that process failed to recognise the nature of secondary teachers' work.
"This is really important. It matters. Because regardless of gender, all workers should be paid the same for mahi of equal value," she said.
She said the investigation was starting with interviews of teachers, which should be complete by the end of the year.
"This is the part of the process that identifies areas of secondary teachers' work that have been traditionally under-valued," Ryan said.
The associate director of the New Zealand Work Research Institute at AUT, Katherine Ravenswood, said the claim was massive, covering a big workforce.
"I think it's potentially a really strong case. They're not going to put a claim in if they don't think there's pretty good grounds for it because the pay equity claims process is quite intense and it is quite long. So it's a lot of effort if you think it's not going to be a pretty sure win," she said.
Ravenswood said teachers' responsibilities and skills were significant as was the impact of their work on society.
"When we're thinking of the kinds of work teachers do, they have to be experts in a lot of things," she said.
Ravenswood said the pay equity investigation would compare teachers work and earnings with a similar male-dominated occupation.
She said a possible comparator workforce might be engineers because they required three or four years of education and the consequences of their work were significant.