“… Suppose a teacher tells the class that he will give them a surprise quiz in the following week. Now, the teacher cannot give the quiz on Friday because when it is Thursday, the whole class will know for sure that the quiz will be on Friday, so it won't be a "surprise" anymore. But the teacher cannot give the quiz on Thursday because the quiz cannot be on Friday (for reason stated above) and when it is Wednesday, the whole class will know for sure that the quiz will be on Thursday, so it won't be a "surprise" either. Similarly, the teacher cannot give the quiz on Wednesday, Tuesday, or Monday. The conclusion is that a teacher can never give a real "surprise" quiz. What is wrong about this (backward) reasoning? ”

====================================
Funny question....Any idea? You can post the answer on my board wor..