Edit: I don't mean to bash teachers, and I appreciate all the work that they do. This post is coming from an experience I had as a kid in school.
I had a teacher in third grade send me to the vice principal's office because my handwriting was, and is, terrible. His idea of dealing with a 9 year old whose handwriting is bad was apparently that if you scream at them hard enough, their good handwriting will just come out. They apparently decided to not inform my parents of this event, so they were quite surprised when I came home and started apologizing because I got in big trouble at school.
Well, my dad went up to the school and showed them he could scream, too. Sent the teacher to the staff room in tears, and the vice principal suddenly lost his volume when he's faced up against a 6'2 farmer instead of a 9 year old. Neither of them tried anything like that again.
My 7th grade homeroom teacher was a poster perfect example of a lazy do nothing teacher. My annual test scores after 7th grade were lower than my 6th grade ones. She managed to be overall detrimental to my skills during an entire year.
My parents were (rightfully) pissed when the results came out. The school was recommending that I redo 7th grade, and I was likely to be assigned to her again.
I'm thankful to how my parents went to bat for me. Yes, there were raised voices at various stages at that point. I ended up in a top flight teacher's 8th grade classroom.
Lupita Nyongo