An independent evaluation says it is likely the design of new NCEA maths and writing tests is unfair on Māori and Pacific teenagers.
It says the difficulty of the tests appears to be about right, but their design and digital nature could be contributing to lower pass rates for some groups.
Meanwhile, just-published results from a September trial of the NCEA tests show improved pass rates for writing and maths, but worse for reading compared to previous trials.
More than 21,000 mostly Year 10 students attempted the September trial with 46 percent passing writing, up from 34 percent in June last year, 57 percent passing numeracy, up from 56 percent, and 58 percent passing reading, down from 64 percent.
From next year teenagers must pass all three tests before they can be awarded any NCEA qualifications.
Some teachers and principals are worried the tests will be too difficult for some students and Māori and Pacific students will be particularly disadvantaged.
A report on the September trial by consultants Evaluation Associates said the achievement gaps for Māori and Pacific students and teens from poor communities were similar to those found in other assessments.
"The disparities in educational outcomes related to ethnicity and decile is a finding which is already well documented in New Zealand research. Such achievement disparities are seen to be related to socio-economic circumstances and ethnicity.
"However, based on teacher feedback, it is also likely that there are some barriers related to the assessment design and accessibility of the CAAs that are contributing to inequities," it said.
"The issues included: difficulties regarding access to devices and the variability in students' digital skills; the additional challenges for students with neurodiversity and other learning needs; and concerns about the question contexts, the method of assessment used, and the level of literacy required to understand the questions (particularly for the numeracy assessment)," the report said.
The report said teachers were worried students who did not usually work on computers were disadvantaged by the online test.
"The system is set up for students who are digitally fluent and when they don't own a laptop they are immediately disadvantaged," one said.
Another said: "The students are severely hindered by the online format with respect to looking at the information provided and then seeing the questions. The students are constantly scrolling up and down… I cannot overstate the significance of this issue, especially considering the nature of these questions."
Teachers also warned that teenagers with attention-deficit disorders struggled.
"Students with eyesight and attention-deficit issues struggled a great deal, as did students generally - reports of headaches, neck strain and exhaustion resulted, and some deliberately rushed to conclusion, presenting low-quality work, just to get some relief," a teacher told evaluators.
Others described the tests as "a huge step backwards for equity in NZ's education system", and "extremely stressful" for some students.
Low decile schools also at a disadvantage
The evaluation report said "disproportionate access to digital devices may be a contributing factor to inequitable achievement rates in the literacy and numeracy assessments for low decile schools and some Māori and Pasifika students".
The report recommended the addition of a calculator for the numeracy test and a spell-check for the writing test.
It said officials should consider giving students the option of sitting a paper-based exam.
It also said the questions used in the tests should use contexts that were culturally inclusive, but also sufficiently neutral that they were not a barrier for new migrants, English-learners, or students in the Pacific Realm nations that use NCEA as their school qualification.
The report said girls' pass rates were about the same as boys in reading and numeracy, but much higher in writing at 54 percent compared with 37 percent for boys.
Pacific students had the lowest pass rates at 34 percent for reading and writing and 35 percent for numeracy, but their figures included students from Pacific Realm nations that used NCEA as their school qualification.
Māori students' pass rates ranged from 34 percent for writing to 45 percent for reading in the September trial.
Decile one schools had pass rates of 20 percent in writing and 30 percent in numeracy, which was much lower than higher-decile schools.
The report said lower pass rates in lower-decile schools persisted even if the comparison with higher-decile schools was limited to students judged ready for the tests.
It said students from poor communities faced more barriers to learning.
In addition, teachers believed the online nature of the exams contributed to the disparity in the tests.
"The standards are co-requisites for achieving an NCEA qualification and the implications of particular groups of students being less likely to achieve them was seen to be significant. There was a clear view from teachers working with these sub-groups that fewer priority learners will achieve an NCEA qualification," it said.
The report said lack of access to digital devices might contribute to low pass rates for low-decile schools and some Māori and Pacific students.