A girl (who probably has Asperger's though it's never stated) struggles to understand why her older brother has been mean to her since they found out she's going to be in his class. The bad feelings are played out over 5 days in a competition selling lemonade, where misunderstandings lead to increasingly nasty behavior. A great story about siblings, with lots of math problems and lessons in capitalism. Sound like too much for one book? It isn't, though I did have a couple problems with the story, such as the near complete absence of adult guidance and a villain who escapes consequences. Still, a nice book but maybe one adults will enjoy more than kids. I'll be excited to see what feedback kids can give me.