The Daily Nous, a website about philosophy, shares the story of Garret Merriam, a professor of philosophy at Sacramento State University. He caught many of his ethics students cheating on a final exam.
Students sometimes use the website Quizlet to cheat by uploading and sharing stolen copies of exams. Merriam shared with Quizlet a copy of his final exam for the Introduction to Ethics course, which consisted of multiple choice questions. But the copy that he uploaded had several wrong answers.
When Merriam graded the exams, he found that 40 of the 96 students turned in answers reflecting the often "obviously wrong" answers that he provided in the faulty answer key on Quizlet. He ran a statistical analysis and determined that the likelihood that these students had coincidentally marked their answer sheets according to his faulty key to be profoundly unlikely.
Merriam confronted the cheaters and about 2/3 of them admitted to the deed. Those who cheated will face a zero on the exam and possibly a F grade for the course.
Some people on Twitter are accusing Merriam of entrapment, but the professor is standing by his decision. The students knew that the university regards looking at copies of exams without a professor's permission is cheating. They will now face the consequences of their decisions.