Who needs paper, because the test room is small, but people sure have a lot of. The instructor may have not enough students do not care, thorough, and thus, must put the paper to prevent corruption of the students.
To paper because the room is small, but the people are many. Invigilator may not have sufficient number of students. Take care not to make a thorough You must include the student's paper to prevent fraud.
To put the paper because of the exam room is small, but the two rotate and many. The test may be not enough students, care not thoroughly. Therefore, to put the paper to prevent corruption of the students.