Autumn has arrived, and at Granite City Elementary School everyone is gearing up for the biggest and best event of the year, the Harvest Festival. The whole school is excited about the games, the contests, the food, and, most of all, the costumes Everyone except Lucy. She doesn't like dressing up, and has no desire to be a fairy princess or rock star, even for one day. But Lucy is excited about the new science unit Miss Flippo has started: the states of matter. Lucy and her friends understand solids and liquids. They're easy. But gasses are more difficult to grasp. When the class goes on a field trip to an orchard and Stewart Swinefest eats too many apples, and gets a serious stomachache, Lucy suddenly understands that even if you can't see gasses they can fill space and expand, and even make you move. And with Stewart feeling better, she has a really great idea for her Harvest Festival costume, too. The second book in a new chapter book series from IRA Children's Book Award-winner, Michelle Houts, Solids, Liquids, Guess Who's Got Gas draws on STEM themes and is aligned with curriculum guidelines to bring a love of science to young readers, inspiring them to start their own labs and explore their world.