It depends whether you consider "teacher" to be a proper noun ( Teacher ), or not ( teacher ). I think we need to think of this as a culture-dependent word. In most English-speaking countries we don't use that form of address at all, so the question never comes up for us.
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It depends whether you consider "teacher" to be a proper noun (Teacher), or not (teacher).
I think we need to think of this as a culture-dependent word. In most English-speaking countries we don't use that form of address at all, so the question never comes up for us.
CJ
"Teacher", with a capital, is correct in this case. You are addressing someone as "Teacher", so it is a title, a substitute for a name, and hence needing a capital just like "Thank you, Mrs Smith" for instance. Compare with "I thanked the teacher", where "teacher" is an ordinary common noun.