Like the other Lessonette® exercises about mens rea, this lesson examines the mental state of knowledge as set forth in the Model Penal Code. It places knowledge in a continuum of mental states and seeks to familiarize students with the rationale for requiring knowledge and for punishing knowledge crimes differently from other offenses. The lesson also presents material to demonstrate how knowledge, a highly subjective mental state, can be proven through inferences of various kinds, and how proof of knowledge of a result might differ from proof of knowledge of conduct.