"Every child is unique and different. It's never boring. It's just so challenging and rewarding and the school places value on the teachers."
McLanachan said she liked that the school was religious.
"It's nice teaching in an environment where you can talk about God. I like the Catholic environment and it's a pretty special little school. We're teaching the whole child. The spiritual aspect too."
She said she was constantly learning in her role and there was nowhere else she'd rather teach.
"When you think about how many children you have had an impact on in 20 years it's quite mind-boggling but a lot of things have changed," she said.
"It's a completely different world in education now."
Forty John Paul College students attended the pair's special assembly. All of there were former pupils of the school and McLanachan said it was nice to see them grown up.
About the school
Principal: Lorette Tiedt (Acting),
Location: Lisa Cres, Mangakakahi
Type: State: Integrated, Year 1 to 6
Roll: 150 (in July 2017)
Gender composition: Boys 61%, Girls 39% (at July 2017)
Ethnic composition: Maori 45%, Pakeha 44%, other 11% (at July 2017)
Motto: Striving for excellence.