Mrs. O'Connor teaches the class about hygiene, but Betsy takes it too far. She becomes obsessed with germs and refuses to play outside or eat anything that could contain germs on them. Mrs. O'Connor has Betsy realize that being clean is important, but other things are also very important in order to maintain good health, too. Then later, the class visits a Planetarium and learn all about the solar system. But when Sarah mistakenly destroys part of the class' model solar system, all of the kids are forced to tell Mrs. O'Connor what happened.