Oh boy, where to start...
Well, I had luck with my teachers before starting high-school. My old teachers weren't terrible at all, without two exceptions:
My middle-school IT teacher came in two flavors (since we had two different teachers), and both of them were terrible. My brother is an IT engineer, and had attended the same school before me. Of course, like every good younger sibling, I had him taught me how to use a computer (I've been playing since I was 5), and so by the time I was attending the IT basics at grade 7 (or 8, my memory is a bit fuzzy), there wasn't much for me to learn.
This caused problems with teacher 1, who was adamant on his opinion that I could not know more than him since I was attending his class, or anything relevant about the subject. (FYI it was a mandatory course so I had to be there) I remember him accusing me of being lazy more than once, and absolutely refusing to believe that I could have completed his assignment a bit faster than the others due to my knowledge. Eventually, I just stopped caring, and passed the course.
Now, teacher 2 was different from t.1 in every wrong way. You see, my brother had been his student, and quite brilliant in math and IT, and so I caught the teacher's eye. The bad thing was, that I am not my brother. I can handle IT if I can get clear instructions, but my math skills are horrible. When I attended the coding course at grade 9, I got to hear about it all the time. He wasn't mean, but compared me to my brother constantly, which naturally irked me. I can't remember how many times I heard the phrase "You're only done this much? Your brother would've finished it five minutes ago." But the good thing was, that he was impressed with my IT skills and was nice to me unlike t.1.
Now, to my high school.
I'll start with my history teacher. If you think that your teacher is cruel because he scolds you for being 5 minutes late, you haven't met such a teacher that I have. Now, before I delve into his bad qualities, I have to say (to his credit) that he is one of the most competent and most excellent teachers that I have ever had. He is harsh, but fair, kind of like a Buddhist zen-master. If he yells at you, he yells from a good reason, and actively speaks about tolerance and against bullying. But there is a reason why our students have nicknamed him 'Professor Snape of [Our school's name]' The most hardened bullies fear this man, and they never backtalk to him. Even the worst class clowns shut up, and sit straight without saying a word. Every paper appears on time, and no one dares to get anything lower than a C.
He's been previously an army sergeant, and so he keeps a very strict discipline in his classroom. You do not speak without his permission, not rise from your seat without his permission, you do nothing without a word from him. When he asks, you will answer. You are allowed to not know, since we are there to learn, but you better learn, and slacking is unforgivable. Once, five of our students were 10 minutes late from his class because of smoking in the bathroom. He got furious when he found out. And I don't mean furious as in 'scowled, and gave detention', but as in 'yelled to the whole class for 15minutes straight like a sergeant to an arrogant soldier' It was terrifying. It was the first time I have ever been afraid in school. I wanted a hole to appear so I could jump into it in order to avoid his wrath. Some of the more sensitive students started crying in the classroom. He apologized to us later, but even now, I fear him as much as I respect him.
And onto the last one, my English teacher. Now, my profile makes it quite clear, than I am not American. I am from Finland and therefore, English is not my first language. Now, I told you earlier that I've been playing video games since I was 5yrs old. I played the same games as my older brother did, and about all of them were in English. I knew how to read at age 5, and again, with my brother's help, I became quite proficient in the language, since I'm good at learning them (probably to compensate my poor math skills).
To give some perspective of my skills, I read books in English. I write fiction in English, and I spend almost my every waking hour playing games or surfing online if I'm not in school. But my last year's English teacher suffered from the same problem as my IT teacher no.1. She could not believe I could know more from the subject than what she had to teach me (Again, mandatory course). I admit, I do not know everything. I have weak points and things I still need to learn in order to get them right, but they were only about 15% of the whole course. I remember her calling me an arrogant, overconfident cow in front of the whole class because I 'wasn't working' when in truth, I had translated my text a good while ago. Needless to say, I don't attend her courses anymore. But oh well, I doubt I'd be able to sway her opinion, so I just let it slide. No one gives a hoot what your grade is, as long as you have the skill to be understood by the people.
I'm sorry about the wall of text. My nightly ramblings tend to become quite long.