Welcome Fifth Graders!

I saw a commercial today for something called GPS. A woman in her car wanted to figure out how to get to a certain store, and she used the GPS in her car. GPS stands for

as this quicktime video explains.

The Global Positioning System uses satellites that were placed in orbit around the earth by the U.S. Department of Defense. They planned to use these satellites for military operations, but now civilians (people not in the military) can use them. The GPS satellites orbit the earth twice a day and send signals to earth. If you have a GPS unit, you can use the signals to figure out where you are on earth.

The 29 satellites that are part of the system orbit the earth about 12,000 miles above us. Here are some basic facts about the GPS satellites:

They move all the time and travel about 7,000 miles an hour.
They use solar energy to get their power and have batteries they use to story energy in case there is a solar eclipse.
Each satellite weighs about 2,000 pounds and lasts about 10 years.
The Department of Defense sent the first one to space in 1978 and the 24th was put in place in 1994.
As one goes out of service, they send up another one to take its place.

Here's a

from NASA explaining how GPS is used by many different people.

On the Google Apps site you just created for journaling in this course, please tell me what you know about how people navigated before we had GPS.

Create a new journal entry titled: How I think early explorers navigated:
In a paragraph or two, please answer the following questions:

Before GPS, how did people know where they were on Earth?
How do you think Christopher Columbus, Lewis & Clark, Isabella Bird, Grace O'Malley, and other famous explorers got from place to place without getting lost?
As a 10 or 11 year-old, how do you usually figure out how to get where you want to go?

Last modified: Tuesday, May 10, 2011, 2:00 PM