It's amazing what people think you don't know.

The other day, I was covering a class that didn't have a teacher. The subject was some basic math. The students thought that because I taught computers, I didn't know this subject. As I was explaining it, I heard one of the students say "He knows this stuff!", I laughed, and she said "I thought you didn't know math! I thought you just knew about computers." So I replied, "I know all about computers and math, I just don't know how to read and write!" That got a few laughs, as well as a few strange looks from a few who thought I was serious. But the students actually think that a teacher knows what they teach, nothing else. One told me that she thought another teacher was the smartest because he teaches basic math, reading and writing. "That's THREE things." Funny.