question tags for sentences with dummy elements

I have a question about question tags.

That is our new teacher, isn't it?

That is our new teacher, isn't he?

Which one is correct?

Solution 1:

I think that 'it' is not referring to the teacher.

'That is the new teacher, is it not (true) ?'

'That is the new teacher, is it not (a fact) ?'

'That is the new teacher, is it not (the case) ?

I believe it is quite correct to say 'it' because the 'it' is not a person but refers back to the fact that 'that is the teacher'.