My math teacher (at a private school) was just a random students' mom. She had no higher degree and only taught the book. If you got the right answer by using a method not included in the book, it was marked half-credit because she didn't understand and wasn't interested in hearing your logic, because "that's not what the book says".

Being taught by people who have no drive for knowledge and just want to teach the standardized test answers SUCKS.