NAVIGATION TOOLS: Using GPS Receivers - Finding Geographic Positions and ASK What is a and how is a geographic position determined? In this section, you will use a GPS receiver to find geographic positions called waypoints. INVESTIGATE Every geographic object on the ’s surface has a geographic position. These positions can be marked by street addresses or other landmarks. GPS receivers are often used to find geographic positions. A waypoint is the term used for the geographic position of an exact intersection of and as marked by a GPS receiver. A waypoint is useful when no street address is available. Imagine if you were in a place with no address, like a forest or the desert, how could you know your exact ? No matter where you are, a waypoint can define your location. Once a waypoint is recorded, the GPS receiver can calculate the distance and direction of a geographic object from your current position. For example, if you know the latitude and longitude coordinates of a gold mine (object), GPS can calculate the distance from where you are and then direct you on how to get to the gold mine. CREATE Find a Waypoint • Make a list of geographic objects that interest you. Your list may include a sign, a tree, a mailbox, a house, etc. You will need to be able to go to the object in order to record the geographic position. • Become familiar with your GPS receiver. GPS receivers need to communicate with , so be sure to go outside where the receiver can get a clear connection. It is best to do this activity when the sky in not overcast. • Go to your selected geographic object. • Find the “main page” screen of the GPS receiver. Select “mark” and then select “ok.” The waypoint numbers (latitude and longitude coordinates) will be displayed on the GPS receiver. • Record the waypoint numbers on a sheet of paper and be sure to mark the corresponding geographic object. This is helpful when you are measuring several objects and waypoint numbers. Determine Distance and Direction • GPS receivers vary on how to specifically determine distance and direction. See your owner’s manual for details or check out the handouts included in this section for different Garmin receivers. • When the GPS receiver is ready to mark a point, highlight the latitude and longitude values and replace these values with the latitude and longitude of your target location. • You may change the name of the point. • The GPS receiver will display the distance and direction you need to travel to your target location. • Depending on the distance, walk or drive to your target location by following the GPS directions. The in the GPS receiver will continuously guide you to your target while you are moving. DISCUSS • What did you learn about geographic positions and waypoints? • Why is it important to understand how to find geographic positions? • How close did the GPS receiver lead you to your target location? REFLECT • How can gathering waypoints help you? • What kind of activities can you do or create using waypoints? • How is it useful to know the distance and direction of a waypoint?

Developed by Dr. Lisa Bouillion Diaz, Barb Roberts, Terri Myers, Dr. Nama Budathoki, Wilbon Anthony, Susan Hayden, and Dawn Waller. University of Illinois Extension, 2011. College of Agricultural, Consumer & Environmental /State/ County/Local Groups/USDA cooperating. University of Illinois Extension provides equal opportunities in programs and employment. http://web.extension.illinois.edu/4hmapmakers/