He made me stand in the hall for 10 minutes before letting me in.
What happened? Do other students have to do this?
Yes, mainly me though but it happens to other students too.
If your teacher is singling you out, talk to another adult or counselor about it, and explain your frustration without blaming the teacher. Try to come to a mutual understanding of why you feel the way you do.
I will do that, I think everyone needs to know.
I am very glad you can see this is so unfair. But you know if this is because you are showing up late to class he might be justified.