Elms Environmental Education Center

Student Pages

How to Use a Compass: Intro

The compass is an ancient instrument invented by the Chineese somewhere around 250 B.C., with all the relevant advances in compass technology refined, again by the Chineese, by the 15th century. The modern compass is nothing more than a magnetized needle floating freely in water. The needle is anchored by a pin in the center, allowing it to spin. The magnetized end of the needle is naturally affected by the Earth's magnetic field, causing the red end of the needle to point north. The needle does not point exactly toward the north pole, but rather to what is called "magnetic north"; a point near Ellsmere Island in Canada (82.7°N 114.4°W) and slowly moving toward Russia at a rate of about 35 miles per year.


What is a compass used for?

  • Locating North, South, East and West (the cardinal directions).
  • Locating a specific bearing (a number between 0-360). "The GPS says I have to walk 500 feet bearing 231 degrees."
  • Determining the bearing of an object/landmark. "What is the bearing to that house over there?"

With a map:

  • Figuring out what direction (bearing) to follow to travel to a desired location. "What bearing do I need to follow to get home?"
  • Determining your location. "Where AM I?"
  • Estimating where you will be in given amount of time. "I'm heading home, but I have to be back before dark. Can I make it in time?"


Bearing: the direction you want to travel or the direction to a landmark.

Heading: The direction you are ACTUALLY traveling in. (Note, this is not necessarily the direction you WANT to travel in!)

True North: The direction to the North Pole.

Magnetic North: The direction the red needle points towards. Not the same as the north pole.


  • The red needle ALWAYS points north.
  • (It is a magnet so be sure there are no metal objects nearby that will attract a magnet!)
  • The "direction arrow" points toward your target.
  • The white line at the base of the direction arrow is where you "dial in" the direction you want to determine.
  • The black dial can be rotated by hand!
  • The "dog house" always points toward "north" on the dial.

Home  | For Students | For Parents | For Teachers | Nursery | smcps.org

The Elms Environmental Education Center is the home of Environmental Education for St. Mary's County Public Schools.

Unless otherwise indicated all original content on this site is free and in the public domain.