I don't know what type of class they were in but the professor didn't have a different copy of the test so all the students in the class took the same test at the testing center. One of the roommates would go early in the day to the testing center and take the test and get a bunch of scratch paper stamped by the testing center. Then when taking the test he would write down all of the test questions on his scratch paper that was stamped and then would sneak the scratch paper out in his bag after taking the test. Then the other roommate would get the scratch paper write all of the correct answers to the test on a piece of scratch paper that was already stamped that day and then sneak the scratch paper with the answers back into the testing center. If a moderator asked about the scratch paper while they were taking the test they would just show them the stamp on the paper and they werent questioned any further. When the next test came the roommates would switch and do the same thing but with the first test taker going second and the second going in first and sneaking out the stamped scratch paper.