Climb Up, Slide Down
Most screws spin round and round. But some screws don’t move at all. Have you ever seen a spiral staircase? It comes in handy when there is not enough space for flights of stairs. A spiral staircase is shaped like a screw.
Now, what if you replace the stairs with a smooth surface? You have a spiral slide!
A spiral staircase is a big screw!
Move It Along
Screws are amazing machines. We use them to hold things together. They also dig holes big and small, and they save space. But they do another important job. Screws can move things.
Think about the drill bit spinning into the wood. As the bit drills the hole, wood shavings come out of the hole. The grooves between the threads carry the pieces of wood up along the bit.
This idea led to an important invention more than 2,000 years ago. In ancient Greece, a mathematician called Archimedes figured out how to use a screw to lift water from a river to irrigate crops.
Here’s how it worked: A large screw was fitted inside a tube. One end of the tube was placed in a river. A worker turned a crank at the other end. The turning threads of the screw pushed the water up the tube and dumped it out at the other end. It then flowed along ditches to fields.
Archimedes’ screw, named after its inventor, has stood the test of time. We still use it today! A screw is a simple machine, but our uses for it are anything but simple!