Teaching is a bit like acting. Outside the classroom door, you put on a metaphorical teacher's hat and are changed into a slightly different person. One who knows all the answers! - which isn't necessarily the case in real life... .
So I become a slightly exaggerated version of myself. I become more enthusiastic, more confident, more lively - probably more eccentric. I repeat things a lot. I talk slowly. I talk fast. I wave my arms around. I hold the floor. (I hardly ever do that in the outside world.) That's why people remember their teachers as being a bit mad. They're just trying to be memorable - so that their students learn. At its most basic, they're trying to keep their students awake.
I often think that in some ways, actors have it easy. No one expects an actor to hand out all the programmes, to make up the words for the show - different every time - to perform for six or eight hours with not much break, to gather in audience responses and then to mark these responses in the evening.
I say this - but I would actually hate to be an actor. Why does anyone do it? Imagine having to audition for every new class you take. And dress up in funny clothes. And have potentially nasty comments published in the newspaper about your classes by people who've never taught, but simply watched other people teaching and think they knew all about it. Goodness, how stressful that would be.
(Talking of dressing up - I took the £60 handbag back to the shop. It was very pretty but a waste of money, since I'd hardly ever use it. I'll carry the £5 one at Daughter 1's wedding. Scottish meanness? - nonsense. Just thrift.)