Dear all,

Please see the following. One of the English teachers on Facebook gave the following sentences and said only the last one is correct. But I think only the second one is OK. I'd like to get your opinion on this.

Thank you teacher. ❎
Thank you, teacher.❎
Thank you Teacher. ❎
Thank you, Teacher. ✅

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.



"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.

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