Simple Machines - D. J. Ward - Bog

"Machines help make work easier, like when you need to lift something heavy or reach way up high. There are six simple machines: the lever, the wheel and axle, the pulley, the ramp, the wedge, and the screw. Can you adjust a seesaw to lift an elephant? What happens when you combine two or more simple machines? Read and find out!"--Amazon.com.