Climb Up, Slide Down

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 also dig holes and save space. But they can also move things.

Think about the drill bit spinning into the wood. Wood shavings come out of the hole. The grooves between the threads carry the pieces of wood up along the bit. 

This explains how a 2,000‑year-old invention works. A screw lifted water from a river to water crops.

A large screw was fitted inside a tube. One end of the tube was placed in a river. A worker turned a crank on one end. The turning threads of the screw pushed the water up the tube. They dumped it out at the other end. The water flowed along ditches to fields. Archimedes’ screw, named after its inventor in ancient Greece, has stood the test of time. People still use it today!

Archimedes’ screw