As I can remember my teachers, my calculus teacher during high school was who could provide my heart with highest level of hatred against anything related to math. I remember I was once asked  to write this equation on the board: lim (x-1)/(1-x) while x tends to infinitive. I was mixed, I didn't know how to solve it, ten seconds fifteen seconds go by and then, pops into my mind. I wrote the solution as this: 0. 
I don't forget his words: "hey man, you mean that's zero? So what's the use of math for such a stupid man as you, my students, see? Why don't you go and study literature instead, or maybe social science mostly suits you, eh? What's your idea? I think you are not going to achieve anything in mathematics. That was the main cause due to which everyone in class laughed at me. I was mixed, I couldn't walk and return to my seat, like an iceman. I sat and though. I tried my chance in English which became my life. I don't know where he is or what he does, but I'm sure once I will appear in his front and ask him why?

A strict teacher is not always doing the right thing to their students but I guess these strict teachers are not in belief they are doing the evil things and they are very likely to justify their acts as decent and appropriate measures for students. 

If you ask me who was the strict teacher for me, I will choose my father. I studied in the same school in which my father was teaching Math and I was not good at Math and a dilly-dally type:) I often made mistake while solving equation and I always wondered why on earth the sign(plus/minus) changed in an equation if I had to take something to the other side of equality(e.g. 2x+4y=5 <=> 2x+4y-5=0). He was strict to me but not for other students which made me angry and sometimes embarrassed:D I hardly asked him any question if I had any. But anyway, in the end, maybe my Math DNA activated and I started scoring good in Math:)