Teacher is an individual who does the job of teaching. The another word used for teacher is Instructor.
We call lady instructor as teacher and male instructor – Sir. But the two terms can be used for both instructors irrespective of either male / female.
Some teachers we know are :-
Elementary School Teachers,
High School Teachers,
+2 Teachers,
Home Tuition teacher,
College lectures & professors.
Some other instructors teaches Music, Drawing, Physical education, crafts etc.