Technical drawing students in Limpopo will rewrite the subject tomorrow after the discovery of an answer sheet in the examination room on Friday.
About 1103 pupils from 59 high schools had to be stopped from writing the exam on Friday when invigilators found that a memorandum with answers had found its way into the question papers.
Students were told through the provincial Education Department to prepare for another exam tomorrow.
Ndo Mangala, spokesman for the department, said students were busy writing exams on Friday when the discovery was made.
"This was purely an administrative error which could not be detected in the printing of the paper. We acknowledge the mistake and apologise to the many pupils who took time to prepare for that paper. They will sit again on Wednesday [tomorrow] and we hope this time they will find it [the exam] easy," he said.
He said they could not take action against any person as the mistake, it was discovered, was not intentional.