Revenge of the teacher's pets

The Brewster triplets, Dawn, Darby, and Delaney, are looking forward to a smooth transition to seventh grade, but from the beginning things go wrong: they are split into separate classes, they end up on the cheer squad (which only Delaney likes), Darby is failing, and Dawn keeps getting into trouble--and somehow they must solve all these problems, help plan their older sister's wedding, and stay together despite the changes that come with growing up.