I had a professor in college who wrote down on the blackboard after each test how many students got A’s, B’s, C’s, etc as professors often do. But then after one test he wrote down the number 13, which was not associated with any grade, and circled it. He then said “Thirteen of you answered “b” for Question 18. Everybody please turn to Question 18.”
We did, and it said “I am not really reading this and am using a file to cheat”
He continued, “this week is your last week to drop this class”
The next time the class met, there were 13 fewer students.
