Global Positioning System (G.P.S.)

Transcription

1 Title: Global Positioning System (G.P.S.) (Navigation) Grade(s): 6-8 Introduction: The Global Positioning System (G.P.S.) Is a worldwide radio-navigation system formed from a constellation of 24 satellites and their ground stations. GPS uses these man-made stars as reference points to calculate positions accurate to a matter of meters. In fact, with advanced forms of GPS, accurate measurements can be made. GPS receivers have been miniaturized to just a few integrated circuits and so are becoming very economical. The basis of GPS is triangulation from satellites. To triangulate, a GPS receiver measures distance using the travel time of radio signals. To measure travel time, GPS needs very accurate timing which it achieves with little problem. Along with distance, the exact location of the satellites is required. Any delays that the signal experiences as it travels through the atmosphere must be corrected. Improbable as it may seem, the whole idea behind GPS is to use satellites in space as reference points here on earth. Learner Objective(s): The student will be able to understand how ships know their location when sailing on the ocean. The student will be able to explain how GPS transmits signals to ships giving the exact longitude and latitude. Florida Sunshine State Standards: Science: SC.H.3.3.6; Math: MA.C.2.3.1/MA.C Competency Based Curriculum: Science: M/J3 - I-1-B; Math: M/J1 - IV-7/Math - M/J3-III-1-A Materials: One Globe One Ball of Kite String Construction Paper (Various colors) One roll of Scotch Tape I-A-36

2 Activity Procedure(s): 1. Allow the students to use their imaginations to create paper satellites from colored construction paper. 2. Show the students a picture of a real satellite. 3. Hang the satellites that the students create from the ceiling with string so that is above the globe. 4. The latitude and longitude can be marked with a different colored string so that the students understand and can see the directions. 5. Select a few students to construct the paper ships that will be taped to the globe somewhere on the ocean. 6. Have a few students take the colored latitude string and cross it through the ship. 7. Allow the students to take the longitude string and cross it through the ship. The point where the string makes an x is the exact latitude and longitude. 8. Allow the students record the location in their notebooks. 9. Have the students place the ship on the ocean for others to find the exact location. Student Assessment: Allow student to answer critical thinking skills questions assigned by the teacher. a. How do you think we know where are ships are located on the ocean? b. What do sailors use to find out where they are when they are on the ocean? Why are lines of latitude and lines of longitude used to locate the position of a ship on the globe? Activity Extension(s): 1. Illustrate why four satellite ranges are needed to determine exact position. (Math) 2. Use a globe and use colored lines to show the longitude and latitude lines. (Geography) 3. Select an article about maritime navigation and discuss G.P.S. correlation. (Language Arts) I-A-37

3 Home Learning Activity: Students will write a report about their notebook findings and share it with the other students. Vocabulary: triangulation, global positioning system (gps), navigation, sextant, compass References/Related Links: I-A-38

4 Global Positioning System Reading Passage GPS, which stands for Global Positioning System, is the only system today to show you your exact position on the Earth anytime, in any weather, anywhere. It is a worldwide radio-navigation system formed from a constellation of 24 satellites and their ground stations. GPS uses these man-made stars as reference points to calculate positions accurate to a matter of meters. The satellites transmit signals that can be detected by anyone with a GPS receiver. Using the receiver, you can determine your location with great precision. GPS is one of history s most exciting and revolutionary developments, and new uses for it are constantly being developed. But before we learn more about GPS, it s important to understand a bit more about navigation. Magnetic compasses and sextants were the most common types of navigation. The needle of a compass always points north, so it is always possible to know in what direction you are going. The sextant uses adjustable mirrors to measure the exact angle of the stars, moon, and sun above the horizon. However, in the early days of its use, it was only possible to determine latitude from the sextant observations. Sailors were still unable to determine their longitude. This was such a serious problem that in the 17th century, the British formed a special Board of Longitude consisting of well-known scientists. This group offered L20,000, equal to about a million of today s dollars, to anybody who could find a way to determine a ship s longitude within 30 nautical miles. In 1735, John Harrison, a Yorkshire carpenter, successfully constructed the marine chronometer having some components of wood and weighing 125 pounds. Because of its precise timekeeping ability, the chronometer, in perfected form, was later to become an addition to nearly every ocean-going vessel afloat. I-A-39

5 Global Positioning System (G.P.S.) FCAT Questions Directions: Read the passage, then answer the questions. Answer multiple choice questions by circling the letter of the answer that you select. Write your answer to the Read, Think, and Explain question on the lines provided. 1. Which of the following navigational developments uses adjustable mirrors to measure the exact angle of stars, moon, and sun? A. Compass B. GPS C. Sextant D. Radio transmitter Answer: C 2. The shipboard timepiece developed by John Harrison in 1761 is called? A. G.P.S. B. Chronometer C. High-frequency amplifier D. Time protractor Answer: B 3. G.P.S. function primarily by? A. Transmitting high frequency ra B. Measuring time of navigation C. Guiding ships for proper direction D. Determining latitude and longitude Answer: A 4. Explain how a G.P.S. measures the exact position on the Earth: I-A-40