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 confus ed . The -ing ending means that the noun described has a more active role you are not making any sense so you are confus ing (to others, including your professor).