Teachers may specify how they wish to be addressed. Otherwise, best is to call them by their title and surname, for example, "Mrs. Brown" or "Professor Smith". Do not address someone as "Teacher".

I am sure that your teacher will tell you. Usually in high school it is Mr/ Miss/Ms/ Mrs Smith [ their title and surname] At university, if the lecturer is a professor then you say Professor Brown, can you tell me more about......? If the lecturer has a doctorate you would say; Doctor Brown, can you tell me more about......?

things would be different in different places,,in china we call our foreign teachers their first name,,,,and we call chinese teachers " family name + teacher/professor "