Unschooled

Allan Woodrow is back with another pitch-perfect middle-grade novel full of hilarious antics, epic arguments, and a fifth grade that just doesn't get along! This year's fifth graders are the worst Principal Klein has ever seen. But he's hoping that Spirit Week can teach them teamwork, with a top secret prize for the winning team as incentive.
Best friends George and Lilly have been looking forward to Spirit Week all year. They might be complete opposites, but they can't wait to be on the winning team together. When their classes end up rivals, with Lilly leading Team Red and George leading Team Blue, the friends swear they can compete and remain best friends.