I gotta say, this idea — a professor intentionally introducing a single falsehood into each of his lectures, challenging the class to find it and expose it — is pretty great for a slew of reasons. Given a sufficiently dedicated group of students (e.g., students who chose the class for a purpose, rather than those who were forced to take the class to fulfill an otherwise-meaningless requirement), it gets the class thinking about the material with a more critical mindset, it exposes areas of the material with unnecessary or unexplained ambiguity, and it serves to reinforce the fact that no teacher should be immune to having his or her lessons challenged by students.

Very smart.