How is your forearm like a lever? * What makes it easy to pull a flag up a flagpole? * How can a windmill help to do work? Janice VanCleave's Machines includes 20 simple and fun experiments that allow you to discover the answers to these and many other questions, plus dozens of additional suggestions on how to develop your own science fair project. Learn how an elevator works using a box, string, a paper cup, and some coins; build a bubble machine...