7-year-old has learned how to whine

[fairefaerie]

DD will turn 7 in two weeks. Without warning, she has learned how to pout and whine. She's never ever been whiney before.

I can deal with whining at home. We pretend we can't understand her until she uses the proper voice. The problem comes with gymnastics. She's been in gymnastics for 2 years, and the whining and pouting has extended to the class. I watched in horror yesterday as she looked at her coach, crossed her arms and set her feet in absolute refusal to follow directions.

How do I discipline her while she's under the care of another adult?

[Thalia the Muse]

I would leave it up to the coach, who ought to be able to work with kids who are being difficult -- I'm sure she's not the first! It might be helpful to warn her that she might not be able to take lessons any more if she keeps refusing to do what she needs to do, because the class may eventually ask her not to come back and give her space to a kid who's more cooperative, though. But I'd only have that talk once, and then let events take their natural course.

[fairefaerie]

Though I believe the coach can handle the mini tantrums, I'm starting to worry that she'll be doing the same thing to babysitters (very rare, so we won't know until it happens). I just wondered if anyone has any tips for explaining to dd how to treat adults that aren't her typical caregivers.