"Mystery Powders" is a popular exploratory activity in which secondary students describe properties of several white, powdery substances by means of observing their structure through magnifiers or dissection scopes, reactions with a variety of liquids, and heat. Once students or groups have determined the properties of the various powders, they are typically given an "unknown" mixture of two or more of the powders and challenged to test the mixture and unravel its composition. Generally, students then report their findings to the teacher, who verifies the ingredients against a prepared answer key. Basically, the answer is either "right" or "wrong." But what if the teacher loses the "right answers?" In this article, the author shares what happened to his class when he once lost his answer key to the Mystery Powders lab. He also describes how that particular event turned the activity from a disaster into one of the best inquiry lessons he has had as a science teacher. (Contains 2 figures.)