How do planes stay in the air? What causes a sonic boom? And how do astronauts go to the bathroom in space? Grouped under the themes Balloons in the Air, Machines in the Sky, and Starships in Space, this profusely illustrated book chronicles the history and evolution of flight for readers 9 to 12. Also included are 12 fact cards on some especially interesting aircraft, a double-sided poster, and 9 paper airplanes in three designs—a historic glider, a military jet, and a space shuttle—with easy folding instructions.