The Qualifications Authority will trial an online NCEA level one maths test with a company, Education Perfect, at 20 schools in September.
A common assessment that takes place before the end-of-year NCEA exam season, the test is administered by schools on one of two days.
President of the Post Primary Teachers Association Angela Roberts however says the Qualifications Authority should not use the private sector to deliver school exams.
Ms Roberts says school exams are too important to be contracted out.
She says Education Perfect has already blundered by announcing the trial on social media before the Qualifications Authority had told teachers.
The Qualifications Authority says the pilot will not count towards NCEA and it has not contracted Education Perfect for any other work. Education Perfect says it is only providing the software that will turn the paper-based assessment into an online one.