a teacher who is in charge of one of the classes into which a school grade has been divided
the teacher in charge of a class
a teacher who gives his whole time to the school
the head teacher
Our homeroom teacher was there before we knew it.
a writing-master
Who's the teacher in charge of your class?
To the teachers.
Who is responsible for this class?
先生へ
Will you take charge of this class?
an instructor of the Sonin rank
the position of headmaster