Mr Thornton said the trial was being run with the company Education Perfect.
It was one of several projects being undertaken by NZQA to test the practicality of moving exams and assessments online.
The authority wants to eventually convert end-of-year NCEA secondary school exams to a test-as-you-learn online format.
"Feedback from the students and teachers as to the format of the assessment will also inform any future work/development on digital assessments," Mr Thornton said.
NZQA chief executive Karen Poutasi has previously told the Herald that her staff were watching developments in online assessment at the university level.
She said the NCEA exam system involved two million pieces of paper moving round the country.
It encouraged online learning but sent students "back to the Dark Ages" to hand-write exam papers.