Every volume of Science Comics offers a complete introduction to a particular topic - dinosaurs, the solar system, volcanoes, bats, robots, and more. Whether you're a fourth grader doing a natural science unit at school or a thirty-year-old with a secret passion for airplanes, these books are for you!In this volume, meet Bea, Archie, Trudy, and Spence, otherwise known as the BATS! They crisscross the globe using every type of bridge: beam, arch, truss, and suspension. From ancient low-slung rope bridges to modern high-tech towers of steel, they’ll traverse ’em all. Along the way they'll identify the dangerous forces trying to bring bridges crashing down, and how to defeat them . . . through engineering!