Three Year 11 Taradale High School students achieved Scholarship Chemistry, a feat principal Stephen Hensman said was likely unprecedented.
Chemistry teacher Martyn Williams said the performance by Nicola Shepherd, Brandon Huang and Lachie Calder was "exceptional".
"They have achieved at the highest level, where they are competing against the cream of Year 13s from around the country - it is a pretty amazing feat by these guys," he said.
The New Zealand Qualifications Authority said scholarship candidates were expected to demonstrate "high-level critical thinking, abstraction and generalisation, and to integrate, synthesise and apply knowledge, skills, understanding and ideas to complex situations".
"They were doing NCEA Level 1 in Year 10 and it wasn't challenging enough, so part way through last year they were put into Year 12 chemistry classes - so they didn't even finish a full Year 12 chemistry course before they did the Year 13 chemistry class, which makes it even more remarkable."
Mr Williams said the students' ability was spotted by teacher Neal Galland.
Lachie and Nicola were unsure of their career direction but Brendon said electrical engineering was "a good option".
They won't take a high school chemistry class again, this year concentrating on Year 13 physics, biology, statistics, calculus and English.
"To be taking a Year 13 course this year, as Year 12s, does make their choice for next year interesting," he said.
While all are likely to be eligible for entry to university at the end of this year they said they would stay at school, picking up more scholarships to help fund university study.
They are eligible for $500 each for their scholarship success but if they can pass three scholarships exams next year it could be worth $6000.
Top scholars nationally could earn $30,000 for university study.
Mr Hensman said scholarship classes were not funded by the Education Ministry and because the school was relatively small, with a roll of 955 students, it could not offer designated scholarship classes.
They were taught outside normal school, with teachers giving their time voluntarily, Mr Hensman said.
"We encourage teachers to provide classes but we can't resource it, so the only way is to do it in one's own time - one class runs at 8am before school starts."