Screw

**What is a screw? **
==== A screw is a simple machine. A screw is an inclined plane that winds around a spiral. A screw is NOT smooth like a nail. Instead, it has ridges. Screws can raise and lower things. Screws also hold things together. ====

**Check out this video clip to help you better understand how this simple machine makes work easier. **
**http://www.schooltube.com/video/da18fac6bab24eae899d/Simple-Machine-Screws **