first off, its normal for kids to act in this manner. kids are after all, playful beings. they will only start to take things seriously once they know the importance of doing good in ur studies.

like kelvint83 said, not doing good as a kid does not mean ur destined to be a drop out or what not.

u cant force a kid to do what they dont want to. its a priority for every parent to have a good relationship with their child. the best way is to subtly let her realize the importance in doing good in studies, dont force it, encourage it.