Students at the Bhagat Pre-University College, in India, were allegedly asked to wear cardboard boxes on their heads to stop them looking at one another's exam papers.
A picture of the students was posted to Twitter and has since gone viral, forcing officials to apologise.
One official said in the apology that the cardboard box wearing was part of an experiment after hearing other schools had done the same.
"There was no compulsory aspect ... You can see in the photograph that some students are not wearing it," a staff member told BBC Hindi.
"Some who wore it removed it after 15 minutes, some after 20, and we ourselves asked them to remove it after one hour."
Education officials in the area told the Indian news agency IANS that they were seeking an explanation for why students were asked to wear cardboard boxes while taking their exams.
"Whatever the purpose, the students cannot be made to wear cardboard during exams," the education spokesperson said.
"There is no rule or advice from us suggesting this is suitable."