The school prefect has also managed to find time to be a member of school bands, write songs, coach a debating team and do karate.
It all means that study time has to count.
Catherine said she discovered an app called SelfControl - "because I don't have any" - which blocks distractions including Facebook and Twitter from her computer.
The phone is also switched off, although music is allowed.
"If I am reading something, then I'm going to need music that I'm not going to be listening to lyrics.
"So there's a best-of-Mozart on Spotify that I quite enjoy. But if it is something like maths, I can leave the radio on in the background."
Catherine said she was leaning towards studying medicine at university. She opted for so many scholarship papers for the challenge, and also the financial incentive.
More than 140,000 students will sit NCEA and scholarship exams between Friday and December 2.
Richard Thornton, deputy chief executive of assessment at the NZQA, said it was now "crunch time", and many students would be experiencing their first big national exams.
Puppies help ease stress for uni students
Puppies, free breakfasts, yoga and a "warm fuzzies board" are some of the ways universities are helping students to deal with stress as they tackle exams.
Linda Lim and Jovana Nedeljkov get to cuddle one of the SPCA dogs.
The SPCA and Husky Rescue NZ have brought in their puppies to university campuses throughout New Zealand.
"Physically and physiologically, it makes us feel more relaxed and calmer. It's also a wonderful distraction," says University of Auckland head of counselling Kimberly Farmer.
The institution's counselling service is experiencing its busiest time of year, with students feeling overwhelmed by study and stress levels rising, she said.
Law student Jovana Nedeljkov, 20, was among those cuddling puppies.
"I've never felt this stressed in all my life ... Holding a puppy made it feel like everything was going to be okay," she said.
The university also introduced a "warm fuzzies board" where students wrote friendly anonymous notes to each other.
"People wrote letters like, 'I like your smile' and 'You're a great friend'," said Rayhan Langdana, from the university's Law Students Society. "By the end of the week, there were hundreds of notes on it.
"When you're studying at tertiary level, you kind of assume it's only you struggling and everyone else seems fine. So it was good for students to participate in stress-relieving activities together."
Meanwhile, the Law Students Society at Canterbury offered free outdoor yoga sessions.
"It was great to get people out in the sunshine instead of being cooped up in the library," said education and welfare officer Jessie Cross.
And at Victoria University of Wellington, around 4000 students were provided with a free breakfast and lunch. Otago and AUT offered the same, and Massey Albany put on study workshops.
End-of-year exams
*International Baccalaureate exams begin this week, and NCEA and scholarship exams start on Friday and run until December 2.
*More than 140,000 candidates will sit NCEA and scholarship exams this year.
*Cambridge International Exams started last month and will run until November 28
For the Herald's full education coverage, click here.
- additional reporting Jess Pullar
