The union is demanding that the Government move faster to resolve the situation and give schools and staff certainty before the end of the year.
"Pay equity processes for teacher aides have been ongoing for the past three years," Nimmo said.
"The mood amongst support staff at recent union meetings was increasingly angry."
Nimmo said the crucial role that support staff play in children's education is not recognised by the current system.
"We endure poor pay and insecure employment to do the jobs we love."
Nimmo and local school support staff have joined a national campaign of wearing black and white to symbolise NZEI's Fair's Fair Mana Taurite campaign.
Mana Taurite is te reo Māori for pay equity and pay equity is a black and white issue, said an NZEI spokesman.
"It means equal pay for equal work and there should not be pay gaps based on gender.
"The Equal Pay Act was passed 40 years ago, yet women are still paid $4 an hour less, on average, than men."
The union said work that is traditionally done by women — such as caring and working with young children — has been historically undervalued and entire sectors of the workforce have been underpaid as a result.
"We are on the frontline of student support," Nimmo said.
"We work with children who have some of the most complex learning needs and if we truly value the learning of those children, we need to value those people who work closest with them."
Nimmo said the key things teacher aides need are significant increases in pay, job security, opportunities for career development and changes to school funding to support those needs.
"We have been bombarding Education Minister Chris Hipkins' Facebook page and he has been responding," she said.
Hipkins said he could not respond to questions on teacher aides because bargaining to renew the current collective agreement is under way.
"The pay equity claim is a high priority for both the Government and the union," he wrote.
"Please be assured that it's one our highest priorities and we're working hard to get both resolved as soon as we can."
The Fair's Fair Mana Taurite campaign extends to early childhood education, kindergarten kaiarahi i te reo teachers and staff as well as school administration staff.