My biology/German language teacher
I had her for 7 years (1st - 7th grade)
She was putting tons of homework after literally every lesson
And never been helpful. I also remember when i had to do a biology project about tropical animals in prolly like 4th or 5th grade.So me and my dad decided to do a nice, big poster that took us about 3 hours straight. I was really proud of it and sure that she will like it. The next day i went to school with it and showed it to my class with a smile on my face. All i heard from her was that there is no description about some of the animals and gave me "D" for it. It made me really upset and ruined my mood for next couple of days.
There was much much more familiar situations like this but currently i dont remember them so well that i could describe them.