PSIMPLE MACHINES SCREWS Nancy Dickmann BROWN BEAR BOOKS
What Is a Screw You have probably seen screws They are used to join pieces of wood together But there are many other types of screws They all have the same basic shape And they all do the same jobs Screws come in all sizes from tiny to enormous 4
A screw is a special type of ramp Ramps are flat surfaces that are higher at one end A screw is a ramp that twists around in a spiral shape 5
