There's a group of Kiwis whose first language is New Zealand sign language, despite being able to hear.
They're known as CODA, which stands for children of deaf adults.
Damiano Agnew, 18, is among them, telling 1 NEWS, "Sign language is my first language, so I started learning it right of the bat, while everyone else my age was learning English... [I] didn't speak at home, didn't hear anyone speaking at home."
He was brought up, alongside his younger brother, by a deaf solo father.
Romeo Agnew, 16, said, "the conversation dynamics change completely... grabbing my dad's attention would be, instead of shouting across the room, it would be stomping so he feels the vibration".
Damiano says the term 'CODA', is "a term that's really only used in the deaf community and there's not much exposure to it elsewhere".
Oliver Leach, 13, is a CODA too. Both his parents are deaf.
"I remember everyone being amazed at how cool it was, and everyone was asking me how to say this and that... I just think it's a pretty unique language," he said.
The three boys, all attending Auckland's Green Bay High School, have celebrated New Zealand sign language week by sharing their knowledge with others.
1 NEWS joined in with one of the lunchtime "taster sessions", which was completely silent as they taught with a slideshow and sign.
Green Bay High School's Assistant Principal says he attended because "I'm just really keen to support these guys here and support the Kaupapa".
"It is a national language and so I think it's important we all have a little experience with it," he said.
Teacher Amber Garrett said she came along to better herself.
"But also I find it really interesting," she added.
"Even watching political addresses I'd rather watch the signer than the presenter as I think it's more interesting and you get more feeling out of it."
Oliver, Damiano and Romeo have tips for those wanting to learn.
"Try not to get mixed up with English 'cause the grammar's different," said Oliver.
Damiano agreed, saying, "it's not just a different language, like how you can speak Chinese, it's really different, the grammar's backwards".
"You'd be surprised at what you can pick up just by looking at the hand signs and watching the mouth movements," he said.
Romeo added, "turn your voice off, use your eyes".
If you follow that advice, they say you can pick sign language up in no time at all.