A Wiltshire comprehensive has been forced to open over the bank holiday weekend after six pupils were faced with taking seven AS papers in a single day.
The teenagers at Malmesbury school were originally scheduled to take 8.5 hours of exams in English literature, geography and critical thinking today.
Malcolm Trobe, the head, said the school had asked the OCR exam board's permission to bring forward three papers in critical thinking to yesterday, but this had been refused.
So Mr Trobe and Pam Carter, Malmesbury's exams officer, will open the school tomorrow for three hours of exams. The pupils will be supervised by their parents tonight to ensure they do not communicate with any students who have already taken the exam.
"This is a significant inconvenience to the school," Mr Trobe said. "I understand that sometimes people have to come in on the day after an exam was originally scheduled. But to ask someone to come in on the bank holiday weekend is a bit much."
Malmesbury pupils are not the only ones facing timetable distress. Niclas Britton, 18, is likely to have to sit an exam at St Cyres school, near Cardiff, on Saturday, June 17, after a similar clash.
He was originally scheduled to take eight hours of A2 papers in computing, geography and physical education. Staff will have to be in school to invigilate if he has to take the exam on Saturday.
Niclas said: "This isn't very good, is it? Having so many papers at once is going to affect my study because I have to revise for all these exams at the same time."
Brian Lightman, head of St Cyres, said: "Students and staff should not be put in this position. There are too many exams."
An OCR spokesman said: "All the boards collaborate with the Joint Council for Qualifications to avoid these clashes as far as possible. But inevitably, with the number of AS and A2s that we are offering, it's not possible to avoid this in every case."
Lost weekend: Niclas Britton, of St Cyres school, near Cardiff, may have to sit an A-level on Saturday