If anyone else had a maths teacher like mine, I wouldn't blame them. He used to turn up ten or fifteen minutes late for the lesson, bore us stiff for ten minutes, set an exercise, then disappear for an extended f*g break till the next lesson. That's if he bothered to turn up at all; he was a city councillor, and this gave him endless excuses to take time off. He was also my housemaster, and was never known to turn up to do registration. We just did what we liked.