Operational funding at the school has dwindled to the point where support staff have had to be dropped and teaching has become a "nightmare" in many classrooms.
Mr Oliver said education was facing "desperate times".
While government funding was being used for building schools in Auckland and Christchurch, schools and early childhood learning centres throughout the rest of New Zealand were "sinking fast", he said.
"There are more children than ever with learning and behavioural difficulties and very limited money for teacher aids which have become vital in today's education environment."
Whanganui kindergarten general manager Trish Taylor-Pope said over the past three years the number of children with high needs in local kindergartens had risen dramatically.
"And we don't have funding any longer ... we're scrimping and scraping just to get by. It's unfair and very difficult."
In Whanganui on Thursday was the "Better Funding Better Learning" roadshow supported by NZEI (the New Zealand Educational Institute, the largest education trade union), the PPTA (New Zealand Post Primary Teachers' Association) and E Tu, the largest union in New Zealand.
Staff on the roadshow bus were handing out printed postcards addressed to Education Minister Nikki Kaye, saying it was time to break the freeze on education funding.
NZEI field officer Graeme Whitworth said thousands had been sent already to the minister with thousands more being signed and sent daily.
The show has toured throughout the South Island, the top of the North Island and Wellington is now in the central region.
"We're targeting the whole country and are determined to make a difference," he said.