Most people don't seem to understand the basics of the New Zealand school system (let's not go into NCEA...), so here's a reaaally quick break down of it all for future reference, basically because I'm super lazy and would rather link people to a page rather than repeatedly explain it to every new person I meet:
In New Zealand, we have three "schools":
Primary School, ages 5-12
High School, ages 13-18
University, ages 18+
Primary school is from years 1 to 8, but sometimes we call years 7 and 8 "Intermediate".
High school is from years 9 through 13. New Zealand's Year 13 is the same as many other countries' Year 12, just named differently. Sometimes high school is also known as college, which can be confusing for people used to the American college - that is the same as university here!
University is often just called 'uni'. Usually people go from around ages 17/18 onwards, but sometimes there are younger students, and of course older people can go to university too.
Got it? Good. :P