More than 600 people have committed to speaking only in te reo Māori for either a full day, a week or the entire month in September.
The Mahuru Māori Challenge, which started in 2014, is an initiative that aims to make Te Reo a normal part of everyday life in Aotearoa.
Auckland Girls Grammar School Māori language teacher Rhonda Reedy Tibble decided she would commit to speaking Te Reo for the entire month regardless of who she was speaking to, or where she spoke it.
She sent an email to every staff member at the school to notify them in advance and has since received many messages of support.
She said although she was a fluent speaker of Te Reo, using it in a mainstream setting would be challenging.
"I recognised, my goodness, this is how my grandmother felt when most people around her wouldn't speak Māori because she could only speak Māori.
"I'd never actually thought what it must've felt like for her to be only Māori-speaking in a sea of Māori and Pākehā who only wanted to speak English.
Ms Tibble said there had been some concern as to how her decision would affect staff who weren't speakers of Te Reo.
She argued staff should hold that responsibility and ask themselves rather how their actions would affect her ability to converse in Te Reo.
"Are we actually going far enough to see that we are enabling those like me who might wish to take this brave step?
"If we don't challenge that space and we don't ask what is the organisational structural responsibility to support [it], how could it ever get to the space of the direct stakeholder, which is the child?"
Wai Wai Wilsons said she had only been learning Te Reo for the last two years. It would be her first time participating in the challenge and she said she was excited to take it on.
"I just need a reason to speak Māori more often because no one I really know speaks Māori.
"I'm just gonna carry around a Māori dictionary with me, and my notebook that I've got from everything I've learned from this year and last year."
Mikaere Pakii, who came up with the idea for the challenge in 2014 with a team of te reo Māori teachers, said he was overwhelmed at how much it had grown.
He said the challenge encouraged people who did not usually speak te reo Māori to do so.
"If we speak Te Reo we actually allow ourselves to be surprised with other people that we might not think can korero Māori.
"We actually found that a lot more people were forthcoming and a few thousand people around the country have learned some reo. We provided the opportunity for them to actually use it out in the open."
He said he hoped the challenge would continue to grow in the future.