"If it was five, it would have been a huge struggle. It was devastating when we got the news," Ms Marshall said. "A two is where we should be."
Ms Marshall said she is resigned to running the school with such few resources.
"The parents don't have any donations; we're just having to make do."
However, around 800 schools' deciles decreased, resulting in more funding per student, including Kaitoke School. Principal Sarah McCord said the additional funding has been welcome, but has been soaked up by essential costs to run the school.
"You would think all is going to be well but basically it just all gets used up on what it takes to run the power and the teacher aides and things, so it hasn't made a huge difference," Ms McCord said.
Deciles are recalculated after the census every five years. But with the 2011 census being delayed by two years after the Christchurch earthquake, schools which felt they were under-funded were doing it tough for a long time, said Allan Vester, chair of the NZ Secondary Principals Council.
"I know a lot of schools would complain they've lost money. The other way of looking at it is schools that have gone down in decile really should have had the additional money earlier. If you were one of these schools, there would be a number of years where you were under-funded according to the real decile," said Mr Vester.
He says funding drops almost never affect the number of teaching staff, but often hits administration staff and extracurricular activities.
Education Minister Hekia Parata has called the decile system complicated and clumsy and is looking at how school funding can be improved.
She said a review into the system was in its early stages, and any decisions were "still some way off".