The clip we heard came from an episode of Real Easy English about teachers - listen to the whole programme.

Ronald Arbini, Tag-Questions and Tag-Imperatives in English, Journal of Linguistics, Vol. 5, No. 2 (Oct., 1969), pp. 205-214 ...

question tags with the imperative Yes, both are correct and there is very little difference in meaning between the two. There is perhaps a slight suggestion that you might be expecting the answer ...

Basically, question tags work by turning a statement into a question by adding a tag at the end. The tag is a short yes or no question, and we use different tags depending on the statement.

We are studying English, aren't we? Yes, we are. This is a conversation English course, isn't it? No, it's a business English course. Tag questions are useful for negotiations, aren't they? Yes ...