Up to a third of students at some schools are getting someone else to read and write their exams for them - but students needing help at many poorer schools are missing out.
Huge gaps between deciles and individual schools in special assessment conditions for the National Certificate of Educational Achievement (NCEA) are raising questions about whether the system is fair.
"It's clear that there are some inequities in students not being able to access these special assessment conditions," said Secondary Principals Council chairman James Morris.
The data, provided by the NZ Qualifications Authority under the Official Information Act, shows that students with special assessment conditions (SACs) increase in line with parents' wealth from just 3 per cent of NCEA students in the poorest (decile 1) schools to 10 per cent in the richest schools (decile 10).
Two schools, decile 5 Piopio College in the King Country and private Mt Hobson Middle School in Auckland, had special assessment conditions for more than 30 per cent of their NCEA students last year.
Private schools Kristin at Albany and St Andrew's College in Christchurch had the highest absolute numbers, both with 125 students with SACs - 23 per cent of all NCEA students at Kristin and 19 per cent at St Andrew's.
Other schools with high SAC proportions were Ao Tawhiti Unlimited Discovery in Christchurch (29 per cent), Bishop Viard College in Porirua (25 per cent), Mt Hutt College (24 per cent), Collingwood Area School (23 per cent), Kaikoura High School and Ōtaki College (21 per cent), and King's College and Samuel Marsden Collegiate Whitby (20 per cent).
At the other end of the scale, almost a third (157) of the 489 schools with NCEA students had no students with SACs. Three-quarters of the schools with no SAC students were in the four poorest deciles.
The SACs are used mainly to hire staff to read out exam questions to students with reading difficulties and/or to write answers dictated by the students. But the staff are a cost which many poorer schools can't afford.
Secondary Principals Association president Mike Williams said schools also needed to fund staff time to assess students, organise special programmes for them, collect data and apply for SACs - work usually done by special needs coordinators (Sencos).
"Secondary schools are not funded to have a Senco. They steal resources from other parts of the school to create a Senco," he said.
"High-decile schools are more likely to have more resources to put into a Senco than a low-decile school."
He welcomed an announcement by Prime Minister Jacinda Ardern last week that the Government would fund 600 Sencos from 2020.
Morris said low-decile schools were also likely to have higher rates of transience and truancy, making it difficult to establish a track record of need for each student to qualify for a SAC.
In contrast, Piopio College's dedicated Senco Caroline Foss tracks every student with learning needs in the school of just 163 students from the time they arrive in Year 7 and organised SACs for 22 of the school's 72 NCEA students last year.
She first taught at the school in 1993 and has seen dyslexia run in families well before it was recognised by the Government in 2007.
"I have the second generation now," she said. "I have the kids of students I taught a long time ago and I can see now that their parents should have had that help."
"The Speld training was huge for me, a real breakthrough," she said.
In turn she trains all the college's teachers to look out for signs of specific learning difficulties. When teachers spot possible cases, Foss uses computerised Lucid tests to measure students' word recognition, reading comprehension ability and speed, spelling, typing speed and handwriting speed.
Students in need get special teaching for three periods a week in Years 7 and 8 and about a quarter of students in each year group have individual education plans, building a data trail to back up applications for SACs when they reach NCEA.
Emma Carter, a Year 11 student sitting Level 1 NCEA this year with reader-writer assistance, commutes to Piopio by car and bus two hours each way.
"I never learnt anything at my last school. All we did was write stuff down that the teacher would write on the board," she said.
"Here they talk to you. It's not just, 'Go off and do it on your own'."