I have come across this:
'Adjectives that are really participles, verb forms with -ing and -ed endings, can be troublesome for some students. It is one thing to be a frightened child; it is an altogether different matter to be a frightening child.
Do you want to go up to your professor after class and say that you are confused or that you are confusing? Generally, the
=> -ed ending means that the noun so described ("you") has a passive relationship with something — something (the subject matter, the presentation) has bewildered you and you are confused.
=> -ing ending means that the noun described has a more active role — you are not making any sense so you are confusing (to others, including your professor).'
Not a teacher at all.