Dig In
When you drive a screw into wood, it’s easier if a hole is already there. That’s where a drill helps. And guess what? A drill bit is a screw.
A motor spins the drill. The tip of the drill digs into the wood. In a few seconds, you have a small hole.
Some larger drills make larger holes. They dig holes in the ground to make wells. They also make holes for fence posts and telephone poles.
Most screws spin round and round. But some screws don’t move at all. Think of a spiral staircase. A spiral staircase is shaped like a screw.
A spiral staircase
is a big screw!
Move It Along
Screws hold things together. They dig holes and save space, too. But they can also move things.
A long time ago, a Greek inventor named Archimedes had an idea. He wanted to lift water from a river to water crops. He used a big screw. The screw was put inside a tube. One end of the tube was placed in a river. A worker turned a crank. The turning threads of the screw pulled the water up the tube. Water came out at the other end. It flowed along ditches to fields. Archimedes’ screw is still used today!
Archimedes’ screw