Ugh, my ds was the same way at 2.5/3yo... I kept trying to enroll him in classes for his age (swimming, gymnastics, etc) and it was awful. He was always the *only* child who wouldn't follow along. He'd either be writhing in the ground or scared of the other kids or running off in the other direction.
In the end, I decided that we were doing the classes for him, not me, and if I had to fight with him to participate, it wasn't worth it -- classes just stressed both of us out. I found he had a lot more fun with regular but unscheduled outdoor play, trips to the McDonalds indoor playland, things like that. At that age, he just didn't have the maturity needed for structured classes, so we stopped trying! I was bummed, but I can't say he was disappointed.
It may be that your dd is exerting her independence, and if classes are turning into battles then you may want to just drop the classes until she's more ready. You can't *make* her sing or dance, obviously, and she probably knows it!
(And at our house, the 4s were *definitely* worse than the 2s.)
