Half used traditional pen and paper and half had their "papers" delivered electronically to their classroom computers.
On Monday and Tuesday, nearly 300 pupils in seven schools have been taking biology, chemistry and physics exams.
Half used traditional pen and paper and half had their "papers" delivered electronically to their classroom computers.
They are the guinea pigs in a project by the Council for the Curriculum, Examinations and Assessment and exam board Edexcel to develop electronic GCSE and A-level exams.
The curriculum council's qualifications manager, Roger McCune, said the pupils were helping to put Northern Ireland "at the cutting edge of educational technology".
"The young people participating in the trial tests are helping to change the very nature of school examinations," he said.
Automatic shutdown
"In the coming weeks and months we'll be analysing the data they've provided to develop the concept of paperless exams."
As pupils logged onto their computers, they got the same test paper that those using pen and paper saw.
At the end of the time allowed - 15 minutes less than for the handwritten versions - the on-screen tests closed automatically and were sent back electronically to the curriculum authority.
What pupils thought
"We have tried to stay faithful to the rigours you would expect in high stakes examinations," Mr McCune said.
Pupils at Ballyclare High School had mixed feelings about the experience.
"I thought it would be a lot harder, but it was really easy to follow. It was a lot less stressful," said Jayne Coulter.
Tom Burch said: "It was hard to navigate through the questions. You couldn't see how many questions there were in front of you, so it was hard to manage your time. You didn't know if you were going to be short of time or not."
Other issues also needed addressing, such as the availability of technology in schools, differences in pupils' keyboard skills, and how to reproduce maths and science symbols that are not on standard computer keyboards.
"All of these issues will be addressed during this and the coming phases of the development work," Roger McCune said.
"I look forward to the day, sooner rather than later, when Northern Ireland pupils become the first to sit live GCSE or A-level examinations in this way."