I made my teacher angry today. I want to send him a message and ask him to forgive me.

Apologizing in private is better than texting. Besides courage, the teacher can talk to you, which will untie the knot more thoroughly. You can start by saying, "Teacher, I'm really sorry for making you angry today. I hope the teacher will forgive me. If possible, it is best to add a bow to the sincere tone. It's hard for a teacher not to forgive you!