Any student can have a bad day. But giving students multiple attempts on exams is fraught with issues of fairness, exam integrity, and student preparation. In this session, we'll discuss a "mulligan" system used in a very large class (300+) that tries to balance these issues using online exams with large "pools" of questions. We'll explore how to determine who shoud be eligible for a "second shot" as well as making sure students are prepared to make the most of it.