The two Balmacewen Intermediate School pupils were required to do a project that had to ''make an impact on the city'' - a challenge they took to heart.
They chose food rescue organisation FoodShare as their focus and decided a bake sale was the best way to squeeze money out of fellow pupils and teachers.
''One teacher blew about $15 on caramel slices,'' Beth said, and altogether they raised about $180.
Rosa worked out that was the equivalent to the cost of sourcing and distributing 540 meals, based on figures supplied by FoodShare that $1 funds three meals.
They have also spent a day volunteering with the organisation - seeing where the donated food comes from and the various food banks and social agencies which receive and distribute it to those who need it.
The girls have also been putting together a documentary on FoodShare that they hope will go up on the www.foodshare.org.nz website.
FoodShare manager Pip Foster said the organisation was run mostly by volunteers so a donation of $180 went a long way.
The organisation has been expanding rapidly since it started two years ago and has distributed the equivalent of 350,000 meals or 117 tonnes of food.
Surplus food is donated by supermarkets, bakeries and other food outlets and distributed directly to about 20 charities, food banks and social agencies.
Volunteer co-ordinator Carol Chandler said people's circumstances could change very quickly, leaving them without enough money for basics.
She said they were always looking for new volunteers to help with collections and distribution.
FoodShare has just moved into new premises in the former Park `N Ride depot near the Dunedin Railway Station which has helped with the rapid growth of the organisation.
''We are thrilled at the new premises. We have a big chiller and a freezer and a dry goods store. Upwards of 500kg comes in most days and goes out the door,'' Ms Foster said.
Founder Deborah Manning is also working on expanding the organisation to other parts of the country.