Year 11 students run the cafe during the morning shift before they go to school from February 10 to March 30.
The initiative, now in its sixth year, has raised more than $25,000 for Nulsen.
Cafe owner Ben Minson said the fundraiser was an important event for the Floreat Forum cafe.
“This involves making coffee to doing dishes,” he said.
“They all learn how to run such a business and all along we raise money for Nulsen.”
Students Blair Sewell, Luke Fowler and Shaun Tetlow said the key to making a good cup of coffee was keeping the customer in mind, having nice frothy milk and keeping a clean coffee machine.
After training with the Australian Barista Academy, which sponsors the initiative, the group of Year 11 students now have a level 1 barista qualification.
Hale School director of development Dave Reed said the school had been in a fundraising partnership with Nulson for more than a decade.
“It’s all about breaking down barriers,” Mr Reed said.
“It’s after hours and completely voluntary.”