From fairy tales, we learn that looking in the mirror is something only the vain do and that nothing good comes from it. But is that so? Are mirrors something only for those people who believe that what's on the outside is more important than on the inside?
Well, not so. The most challenging question any leader (trainer, manager, parent, team member) can ask is: "I see/notice that you are doing … can you tell me why? By asking this, you confront somebody with behavior you do not understand and consider it the wrong action or response at the wrong time.
And then, please let the other reply. Listen to the answer without prejudice, assumption, or taking it personally. Because if somebody is doing something wrong is most of the time not because they want to. But they don't know anything else to do and don't have the tools or abilities. But, on the other hand, that same person wants to do better next time and, with your help, will do so. Also, what if this person misunderstood your instructions? Did you think about that?
Taking time for Q+A?
Taking time to answer somebody the 'Why are you doing it this way question' will tell that person you care for them. Because why else would you make an effort to notice them and try to find out the why and how (to make things better)? It is also very confronting for that person, so you must respect the wording and conduct. Be sensible and open-minded in finding a solution to improve the other's behavior and decision-making.
So asking why is like showing somebody their behavior in the mirror, which is not for the faint-hearted because it is not easy for that person. So you can use mirrors to look both in and outside. Whether your hair is well, but your conduct too.