Early Discoveries: Astrolabe, abacus, compass, camera. . .the science, the models and YOU! (Crafty Inventions)

Progress has led to more exciting inventions in this title of the Crafty Inventions series. Find out why astronomers developed the astrolabe, learn how military signals led to the invention of the kite and how the abacus made arithmetic easy. Then get your bearings with your own working compass, look through a pinhole camera, rig-up a model boat and cast a jelly hand.