The reason I would not write to my teacher the way I write to my friend is because the way you should be writing to your teacher is with respect and be professional.
When you are writing to a teacher you are required to write professionally, respectfully, and formally because they are your superiors and you should speak to them with respect. When you write to a friend you would typically use slang and informal language use because they are your equals.
You would most likely say something like "Dear, Ms. Thomson, I hope this message finds you well. I have contacted you to inform you of a current problem I stumbled uopn while completing a question to one of your assignments."
If you were speaking to a friend you would probably say something like:
" Yooo whatup? How u been? Can you help me on this problem I have no idea what to some"
Laurie was misbehaving at home. Jackson learned that there was in fact no Charles and that Laurie had been the one pulling the pranks that he blamed on "Charles"