Practicing what wew have learned about assertiveness

Last day, we were said to write in a piece of paper twwo different situations where we had been criticized. In  that paper we had also to describe our behavior inthose situations (if we had been assertive or not).
I had been assertive in one of the two situations: I was talking to a friend and another friend interrupted me. In a good way I told him not to do that while I am talking with someone because the speech can be important and it's a sign of disrespect.
That's was quite bizarre because I saw that what we have learnt in this class serves in usual life situations!