During my senior year of high school, I took AP chemistry. (I know, you're very impressed.)
I had possibly the worst teacher in the history of the world, Dr. Alkaline. Her idea of teaching involved copying our textbook onto the blackboard verbatim, without any sort of explanation or demonstration. It was painful.
One day, Dr. Alkaline had to do some calculation that involved conversion of units and she incorrectly converted cubic centimeters to cubic meters. It wasn't a careless error, but rather an intrinsic misunderstanding of basic unit conversion.
I was a math team dork, so I pointed it out to her. Dr. Alkaline told me I was wrong. The guy sitting next to me, a fellow math team dork, chimed in that I was correct and she'd done the calculation incorrectly. She continued to insist she was right.
Until the next day, when Dr. Alkaline admitted in class that we had been right. At least she owned up to it.
And most baffling of all, Dr. Alkaline had a PhD. We had to call her Doctor. Is that mind-blowing or what? We wondered what the PhD could possibly be in. Definitely not chemistry. Do they award PhDs in stupidity?
Moral: If you're going to teach AP Chemistry in a magnet high school, try to know basic math. Otherwise your snotty students are going to talk about how dumb you are for the next 15 years.
Bonus question: How many cubic centimeters are in a cubic meter?