Teachers are worried compulsory NCEA literacy and numeracy tests will be too tough for new migrants, refugees and international students.
They warn that failing the tests in reading, writing and maths will have long-lasting effects on young people's lives because, from 2024, they must pass in order to receive any NCEA qualification.
Pilots of the online tests have indicated that students who were not fluent in English will struggle.
An evaluation of results from a mid-year pilot said 84 English language learners participated with 35 percent passing the reading test, 21 percent the writing, and 24 percent the numeracy.
That compared to a pass rate for all participants of 67 percent for reading, 35 percent for writing and 65 percent for numeracy.
Sarah Roper from Teachers of English to Speakers of Other Languages Aotearoa New Zealand (TESOLANZ) said vocabulary was a particular barrier for students sitting the tests.
"We've seen the tests and the tests are really difficult for English-language learners. The vocabulary is far in excess of what an English-language learner's vocabulary would typically be," she said.
"These tests are unfair for students who come into New Zealand, who've only been here two or three years, because they haven't developed that vocabulary yet."
Roper said the tests included low-frequency words that students might not have learned, as well as Māori words, which added another layer of complexity for new-comers.
She said the tests could have a big effect on students' future lives.
"It's not going to set people up for success. Our migrant community deserves to be successful... and these tests are going to mean that a whole group of people are not going to get their high school qualifications."
Roper said the government should rethink the co-requisites and make them a separate qualification rather than a requirement for achieving NCEA qualifications.
"When they get their NCEA perhaps it could be endorsed with literacy or not and that would mean they would still be successful in getting their level 1 NCEA," she said.
"These students, they have functional literacy to go about their daily lives but because they can't pass this test that shouldn't be a reason that they can't go on and do tertiary study or get jobs."
Macleans College deputy principal Tina Mair said the school had a lot of new migrant and international students, with 60 different nationalities represented.
She said she agreed with the need to improve literacy and numeracy, but that the tests had words recent arrivals could not be expected to understand without a glossary.
The tests included Māori words such as pepeha, and slang words such as 'glitchy' and 'twerking' and the phrase 'she'll be right'.
"For a newcomer that would throw them completely," Mair said.
In the writing test trialled in the middle of the year, students were asked to write about one of New Zealand's best role models, she said.
"This is the kind of thing really which we can see tripping up second-language students who actually are literate," she said.
Mair said students who had been in the country for several years would be more likely to pass the tests but international students might be deterred from enrolling in New Zealand schools if they saw the tests as a stumbling block.
Universities New Zealand chief executive Chris Whelan said universities were not expecting the tests to affect enrolments from foreign students who completed their schooling in New Zealand, because the University Entrance requirements for literacy were higher than the new NCEA standards.
"There is therefore no change for international ESOL students," he said.
Schools International Education Business Association chief executive John van der Zwan said schools were worried about the effect on foreign students.
"They are worried, they're not sure how it's going to impact on them. There's certainly a recognition that there's going to be more support needed for international students to make sure that they can pass that co-requisite test," he said.
Van der Zwan said some students might decide to start their New Zealand schooling earlier so they had more time to improve their English before they sat the tests.
"It could extend the time that international students need to be here to achieve their NCEA qualification," he said.