Do your kids know how to make a compass using materials found around the house? Does a compass point to magnetic north or geographic north (and what is the difference)?
Join us as we learn about DIRECTIONS as part of our geography lessons.
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This week our North Star Geography lesson offers a hands-on activity showing us how to make a compass and determine “north” using magnetic declination (the difference between geographic north and magnetic north).
North Star Geography is available for immediate download as a ebook. As a Brand Ambassador for Bright Ideas Press we have received a copy of this new program and we will offer you insight about how this program is working in real life with our family.
The Compass Rose
In our last Geography Activities Post we talked about Atlases. Atlases are filled with maps of many forms – political, thematic, outline and more. One element every map will have in common is a Compass Rose.
A Compass Rose is figure on a map which shows the cardinal directions North, East, South, and West. Ordinal directions are often included as well — these are northeast, southeast, southwest, and northwest.
How do you orient yourself using cardinal directions? You first need to know which direction is north.
How do you find out which direction is north? With a compass!
“The first compasses were made from lodestones – naturally magnetic rocks. If a sliver of a lodestone was suspended so it could turn freely (say, in a bowl of water of hung by a string), it would automatically orient itself so that it pointed north. The reason for this is that the earth functions as a giant magnet, with the North Pole and the South Pole working as the two magnetic ends. The earth has such a strong magnetic field that the lodestones are affected but it. Later, people used lodestones to magnetize needles, which were put into compasses.”
Are you ready to make a homemade compass and determine which direction is north?
Here are the supplies you will need:
- Sewing needle, nail or paper clip
- Bowl of water
- Small piece of buoyant material such as a piece of cork, paper, foam, leaf, etc.
Now that you have used a compass to determine north you should be able to orient yourself using cardinal directions, right? Actually, the answer is NO!
Did you know there is one problem with compasses? A compass will point in the direction of the magnetic North Pole; however that is DIFFERENT than the true geographic North Pole!
The magnetic North Pole and the geographic North Pole are about 500 miles apart. In addition, the magnetic North Pole moves at a rate of about 35 miles per year. The deviation between the two North Poles is called magnetic variation or magnetic declination.
If you are using directions to guide your travel you want to move in the direction of true geographic north and not magnetic north, therefore you need to make a few adjustments.
“To compensate, researchers have made charts of declination that illustrate how much distortion your compass shows depending on where you are on the planet. In my hometown, the magnetic variation is about 11ᴼW – meaning that if I want to travel true north, I need to rotate east about 11ᴼ before I start moving.”
For more information about magnetic declination, visit the Geospatial Training and Analysis Cooperative.
To determine the declination for your hometown, you can use the NOAA National Geophysical Data Center Magnetic Field Calculator.
Be sure to use the printable How to Make a Compass & Determine “North” to record your data!
We hope your family has fun learning about directions!
Check out another hands-on Geography Activity – how to make a Karst Cave.