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 seriously 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.