This article discusses how amusing mistakes can make for serious language instruction. The notion that close analysis of language errors can yield insight into how one thinks and learns seems fundamentally obvious. Yet until relatively recently, language errors were primarily treated as indicators of learner deficiency rather than opportunities to consider a student's individual cognitive context and so reconsider and adapt instruction. Through close analysis of the errors made by basic writers, Mina Shaughnessy's groundbreaking "Errors and Expectations" explores the need for teachers to consider the "whys" behind apparent mistakes. Shaughnessy argues that the aspects of basic writing that most frustrate teachers--seemingly sloppy surface errors--often carry unseen educative potential. Inspired by Shaughnessy's open-minded approach to student error, the author suggests playful ways to learn from mistakes. Many classroom activities are described. (Contains 2 figures.)