I agree with polarbear--different kids are good at different kinds of math, and math comes in all flavors. My DD has high achievement test scores for math but she really struggles with math facts and fluency. I can see how her teacher might think she's "slow". But she has no problem with advanced concepts and reasoning ability. I breezed through geometry, physics, statistics, etc. in school but had a horrible time with arithmetic and alegebra. I really did not start getting good grades in math til middle school after all the drill and repetition with math facts (and I never DID learn the math facts very well--but now finally know them after watching my kids play Big Brainz ad nauseum over the summer).

I think it will help to find out what specifically she is struggling with. Is she a kid who is good at arthmetic but struggles with abstract concepts? Or vice versa? And then decide if she is likely to continue to struggle in higher grades/levels or if this is just a phase.