Sounds like the overly dependent, helpless type who (usually) does not realize what a pest she's being or how she robs others of their time in order to help her. I agree, it's a tough situation, but there's no help for it other than being pretty frank with her. She won't improve otherwise (may not anyway) and the rest of you are inconvenienced and irritated. If the instructor can't or won't lay it out for her then I think a couple of you are going to have to, in your "kind but honest way" as my boss used to say.
We used to have one of these in our family -- but she was more of an attention hog than truly helpless...and frankly, more than a little lazy. When we couldn't ignore her, we were fairly honest....though I hate to tell you, she never really changed. It was just who she was.