I have encountered many many students with degrees in voice performance of various kinds who do not understand the process of breathing for singing. It is RARE to find someone who both understands and executes a way of breathing that makes sense within their own body, and who can also explain that behavior in clear simple terms.
So what is up with that, exactly? How can you study singing for 4, 6 or 8 years and not have your body under control such that you can breathe deliberately when you sing and use what you have in your lungs with efficiency?
And, from the standpoint of the teacher, what is the point of talking about breath support if all you can do is say “breathe down low” and “use your diaphragm”. We sometimes think these generic ideas have gone away, but no, not by any means have they disappeared. When a student can explain reasonably well what is supposed to happen (which is a good thing) they may still be unconscious about the fact that what they have described and what they are doing may not match.
If you teach singing, after you teach breathing, make the student demonstrate what they think you said and have them explain to you what you want them to do. Be sure to query the student until you get an answer that makes sense and is being correctly executed by the student. It doesn’t have to be perfect, as most breathing takes time to develop, but it has to be in the ballpark of a good pathway and only you can decide if that is what is happening. The physical behavior has to be there correctly, if only in fledgling form.
ASK your students, what are you trying to do? What do you think I want? What’s happening when you do that? Where is your body moving and in what way? Can you move somewhere else? How does that feel? Is it hard? Why is it hard? Make them focus on themselves and the physical process of DOING. If it looks wrong, it is wrong and you need to go back, find a new way of explaining and do it again. Don’t blame the student, find another way.
And, if you do not understand why a special way of breathing is necessary for singing (and, no, it is not for “resonance” purposes), then you should take it upon yourself to find out.