correct preposition "in" or "on" or "at"

[edmondjanet]

I am in teaching.
I am on teaching.
I am at teaching. Which one is correct?
The first and second I have heard many times.
Thank You.

 

[Barb_D]

Many times?
I teach. I am a teacher. Those are things I have heard many times.

Of the ones you propose, only "I am in teaching" could work -- the others are impossible.

 

[freezeframe]

I am in teaching.
I am on teaching.
I am at teaching. Which one is correct?
The first and second I have heard many times.
Thank You.

I am in teaching.

This means that my job has to do with teaching. Although it would more natural to say "I'm in education".

Similarly: I am in real estate (I work with real estate); I am in retail (my job is in the retail field)

The other two -- I am on teaching and I am at teaching -- don't mean anything on their own and are incorrect.

You can say "I am good at teaching" but not "I am at teaching".

I can't think of any way to use on here.