Screw

Screw:  A screw is a simple machine that is made from another simple machine.  It is actually an inclined plane that winds around itself.  A screw has ridges and is not smooth like a nail.  Some screws are used to lower and raise things.  They are also used to hold objects together.

Some examples of screws are:

•  Jar Lids
•  Light Bulbs
•  Clamps
•  Jacks
•  Spiral Staircase
•  Can you think of any other examples?  Post your answers here.