Re: Shy kids
There's a HUGE difference between introversion, shyness, general (or social) anxiety...and what sounds like a little legitimate fear of physically demanding situations.
Does the school have a counselor or other pupil personnel staff who could work with you to get your DD more comfortable with these situations? I don't think that forcing her to participate will do anything except become a power struggle...you'd probably get further by building her investment in changing her behaviors, KWIM? And school support (or even professional support) might help you do that. B/c there are negative implications if she doesn't change, I agree with you that it's important. Does she understand that she might have to go back to PT? Does she want remediation/additional help for things like singing?
The other thing is that if she's legitimately struggling with severe shyness, introversion, anxiety, etc., an art charter school with such an emphasis on performance is just not a good fit. I love the arts, but I am NEVER going to get on stage and perform. I just can't do it. I tried chorus for a term b/c I do enjoy singing...practices were great, but a near-panic-attack before the recital did clue my mom in to that maybe not being a great outlet for me. I think I was 11. It took a lot of work, but I can do public speaking without giving away my fear and panic...that doesn't mean that it ever went away, I'm just better at hiding it. Some of that may be necessary, but it needs to be on her terms & in her time. Just because she loves music & dance doesn't mean she has to specialize in it or be a performer...it's okay to do something just for the sake of liking it & the joy it brings, as an avocational interest, even in the absence of a drive to perform.