Some Norfolk students sitting exams this summer could be put on overnight 'lock-down' as timetable clashes mean they have to wait to sit their tests, school staff have claimed.
A-level students started their exams on May 20, a week after GCSE students began theirs.
Exam boards draw up their timetables months in advance - but senior staff at Norfolk sixth form colleges say this planning doesn't guard against clashes which lead students to sit exams after their peers.
Dave Brook, co-director at Dereham Sixth Form College, said students occasionally had to wait a few hours if two exams were scheduled for the same session, during which time they would be monitored and not allowed any means of communication.
Some pupils may even have to wait overnight - with the same stringent conditions - if more than two of their exams are scheduled for the same day.
He said: "It is not uncommon because there is more than one exam board. If you are a student sitting subjects with multiple exam boards it is not guaranteed you will not end up with a clash.
"On rare occasions you get people who have three exams in a day. The exam boards have a system which has been in place for many years. There are strong criteria that the parents, student and exam centre agree to.
"The students are supervised between the two exams. The student does not have their phone or access to the internet and is not allowed to speak to other students.
"The risk for students found to have been involved in malpractice is they could be disqualified from all their exams. Students would not want to jeopardise their chances."
Dr Catherine Richards, principal at East Norfolk Sixth Form College, said with a roll of almost 1,600 students the school regularly experienced exam clashes.
"It is more unusual to have people on lock-down overnight but certainly we have had to do it in the past," she said.
"We have two sessions in a day and we make a lot of exam access arrangements for our students as well. Dealing with popular subjects we might have students in 10 different rooms, if there are students with additional needs or if there has been a clash and they need to be kept away from their peers."
Dr Richards added that the sheer number of examinations now being scheduled - including AS and A-levels, GCSEs and B-tec exams - could increase the likelihood of clashes.
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