In this activity Norbert and Zot are world travelers. Your student's job will be to locate them with the GPS. Every time they click on Norbert and Zot, Norbert and Zot travel to a new location (sometimes up in space!). Norbert and Zot will send you their distances from three of the color coded satellites above the earth to your students. They will have to enter the distances into the GPS boxes at the left and then locate Norbert and Zot by pressing the appropriate trilaterate button for their system of three satellites.
You will need to explain trilateration. On a flat surface, like a computer screen, if Norbert and Zot are say 124 units from the green satellite, then they are somewhere on a circle of 124 units with a center at the green satellite, but that's all we know from the green satellite. Your students and you should draw this on paper as you give the explanation to get a more clear picture. We also have the distance from say the blue satellite, so we can draw a second circle. Two circles that cross will have two points where they intersect (They could touch at one point, but that's a special case.) So to locate Norbert and Zot, we need a third circle from the red satellite, which will intersect at only one of the two points most of the time. That's trilateration!
When then circles all intersect at one point and your students see where Norbert and Zot are, then they must identify the place. They could use an atlas or world map to help them. This activity can be used to teach geometry and geography and you can present it in fun and challenging ways.
Be sure Squeak is installed successfully on your computer. It will take about 30 seconds for the project to load for a fast connection (up to 10 minutes for a slow modem connection). Wait until you see an orange flap at the lower left labeled Navigation. Click the flap to open and close it and access some neat tools. You need to click Escape Browser so you will have more space. Click Browser Reentry to get back your Browser controls.
It's much more fun to play with the activity and they will understand trilateration better when they do. Click on the GPS button at the left to see how it works before you try it in class, but return to this page for extensions once your students are familiar with the activity. Two of the extensions challenge your students under your guidance to create Squeak projects of their own by modifying the GPS challenge. When they are done go to the NASA CONNECT web site and submit their versions of the Squeak project and we will post all that work correctly for others to learn from and enjoy.
Math Objectives:
- Students will learn some geometry theorems. Specifically they will learn that it takes three crossing circles to determine a point in a plane and that the centers of the circles must not be on a line. The specific theorems aren't nearly as important as the experience exploring geometry and seeing how it can be used in a practical application. Also students may learn more geometry theorems through exploration in Squeak.
- Students will learn about spatial dimensions. The activity is an excellent jumping off point for exploring the difference between two and three dimensions by researching how a GPS works in three dimensions and comparing it to the activity in two dimensions. Then they can think about how a GPS would locate positions in a one-dimensional world.
Technology Objective: - Students will learn how a GPS locates positions on Earth.
Geography Objective: - Students will learn where places are on the Earth.
Teacher Information:
