Some students arrive at high school with a reading age of only 10, a Tauranga principal says.
Otumoetai College principal Dave Randell said five of the school's year 9 students began the year with severely compromised reading skills.
"Most teenagers at 15 have about 20,000 to 25,000 words in their vocab, these kids have about 10,000."
New research from the University of Canterbury indicates children with reading problems could be identified as soon as they start school. The test could also be a "red flag" for dyslexia.
Mr Randell said the research was good news for teachers and students at all levels. About half the school's 406 year 9 enrolments this year were below the required reading level.
"That technically means half of the students already had a reading problem when they arrived at high school.
"They are going to suffer in the secondary system."
Developed by Dr Karyn Carson, the new research uses results from a simple computer test to predict a child's reading ability at a future date.
Mr Randell said the college's seven feeder schools - six primary and one intermediate - all wanted more reading support and systems for their students.
"If it can help with [dyslexia], that is great too."
The test, which assesses how well a child can identify sounds and words, takes about 10 minutes to administer.
Dr Carson's supervisor, UC's College of Education pro vice-chancellor Gail Gillon, said the test could predict with 92 per cent accuracy what a child's reading ability would be one year after it was taken.
During the phonological test, children were talked through different activities by a female voice and asked to match pictures with their corresponding sounds.
"There might be a slide of a dog and they have to find the other picture that will come up on the screen that will start with the same sound that 'dog' does," Professor Gillon said.
And because it assessed a child's phonological awareness, the test could also be an early indicator for dyslexia, estimated to affect 7 per cent of New Zealand children.
"One of the strong features associated with dyslexia is a phonological awareness difficulty," Professor Gillon said.
"As an early screen it would be one red flag [for dyslexia] ... but it would need to be looked at in conjunction with other things."
The test had been taken by children as young as three years and also those with disabilities.
The computer trial last year involved 95 year 1 pupils, who were measured for reading fluency and accuracy six months and 12 months after they took the test.
The six-month results were 94 per cent accurate, which was even better than the 12-month results, Professor Gillon said.
Researchers hoped to release the programme free to schools once it was finalised.