Maddy Lintern, 16, from Manurewa, said she thought the workshop was going to be boring. She had never budgeted before and didn't want to.
Now she wants to get her first job, sign up to KiwiSaver and buy a house.
Class members played a game where they pretended to be stranded on an island and were given 16 things they could bring with them. That was then whittled down to eight, and again to four.
The last four items they chose - water, a blanket, a cow and first aid kit - showed the youngsters what they really needed as opposed to what they wanted, Lintern said.
"You should always go for what you need. What you want comes after. You should save for everything you need first."
Sophia Matafeo, 17, from Te Atatu, was shocked when they calculated that everything she spent in a year added up to thousands of dollars.
"Most of us don't even have jobs. It was very scary."
It made Matafeo realise that she needed to save for unexpected events. She called the workshop "life changing".
"I think it was life changing for everyone. It gave us an opportunity to learn something about the adult world we're not exposed to very often."
The teens were introduced to financial capability basics, including budgeting, taxes, and savings. For many it was their first visit to a corporate office and their first time learning financial basics.
The class was part of the Prime Minister's Youth Programme, which is for youth who have faced challenges in their lives and are now positively moving forward or who are showing the potential to do so. For example, young people who have moved away from low levels of offending, truancy or poor academic performance and have made a sustained attempt to make positive life changes.
Youth Town chief executive Paula Kearns said being money savvy is one of the cornerstones of a successful and fulfilling life.
"Financial capability is one of the more valuable gifts a young person can have, and it can determine the course of their entire adulthood."
The workshop was put on by AMP, Youth Town, the Ministry of Social Development and the Commission for Financial Planning.
Youth Town plans to include the workshop in its after school and holiday programmes soon.