I regularly ask my own students to challenge what is being said in the classroom. I advise them to question everything they hear, read or see, to help develop their critical thinking abilities, to practice defending or attacking a theory, to exercise their evaluative skills. I read recently of one professor who deliberately lied once each lesson, and challenged his students to detect the lie. As the lies became more subtle, the students began to struggle to detect the falsehood, until eventually they were at the point where they were deeply scrutinising everything that was presented in the lesson, and going beyond the content to make sure they had discovered the lie. They had to discuss extensively to put themselves in a position where they knew what was correct and what was incorrect. The web is a very fertile place to learn, but we all need to develop our critical awareness of what content is good and what is to be avoided.