Educational Activity

Title: Plotting to Get Out!


During this exercise, students will:

· Read and interpret maps
· Orient Guam's global position relative to their own location and other worldandmarks
· Recognize the importance of scale on maps
· Given the latitude and longitude of a point, plot its location on a map.
· Given a point on a map, determine the longitude and latitude of that point
· Make informed decisions about when to round off minutes/seconds.
· Use seconds of latitude to determine distances

Background Terms for Teachers:

Latitude - The angular distance north or south of the equator, measured in degrees, minutes, and seconds along a parallel, as on a map or globe.

Longitude - The angular distance on the earth or on a globe or map, east or west of the prime meridian, and measured in degrees, minutes, and seconds. The prime meridian is in Greenwich, England and is considered to be at 0 degrees of longitude.

Nautical Mile - A unit of length used in sea and air navigation, based on the length of one minute of latitude. One nautical mile is approximately 1.15 statue miles.

Materials needed:

a) globe or world map with lines of longitude and latitude
b) rulers
c) local map of Guam (provided)



Students should locate each of the following world locations, and determine the longitude and latitude of each.

· Their home city/town
· Guam
· Washington DC
· Hawaii
· North Pole
· South Pole
· Paris
· Johannesburg, South Africa
· Riyadh, Saudi Arabia

Adaptation for K-6

As a group, have the students examine a large globe or world map and orient students to the various parts of the world.
· Start with the students' location (country and city)
· Identify all of the continents
· Introduce the Equator to distinguish North from South
· Identify each location on the list as a Country, City, State, or geographic location.
· In small groups or partners, have students search for each location by first identifying on which continent the location is, which will help them narrow down their search

The following are the latitudinal/longitudinal coordinates for each location:

Students' home city/town [Variable]  
Guam 13^ 27 N 144^ 45 E
Washington DC 38^ 54 N 77^ 2 W
Honolulu 21^ 19 N 157^ 52 W
North Pole 90^ N 0^ W/E
South Pole 90^ S 0^ W/E
Paris 48^ 50 N 2^ 20 E
Johannesburg, South Africa 26^ 10S 28^ 2 E
Riyadh, Saudi Arabia 24^ 41 N 46^ 42E


Map 1 is a local map that includes Guam and part of our research area. When we left port, the ship's captain had to navigate the ship out of the harbor, around Guam, and then out to our first research site.

The following are the key waypoints that the captain used to get there. Students should use the supplied map to plot the coordinates of each waypoint and draw lines that connect the waypoints in a sequential order. This is the path that the ship took.

WP #1 LAT 13^ 27'00'' N
LON 144^38'30'' E

WP #2 LAT 13^27'00" N
LOG 144^35"30" E

WP #3 LAT 13^ 42'30'' N
LON 144^51'30" E

WP #4 LAT 13^43'00" N
LON 145 E


Discuss the difference between the first world plots and the second local plots. Here are some possible questions to help facilitate the discussion:
· How was plotting on the second map different from the first?
· How does scale play a factor in showing distances?
· Why were the first two waypoints so close together?
· When are minutes and seconds significant, and when can you round them off? List situations where an error of a few seconds could be disastrous.
· How would you round off minutes and seconds? How is that different from when you round off using base 10 numbers?
· What is unique about the North and South Poles?

During the discussion, the importance of the seconds should become apparent in practical situations such as navigation in small harbors.


Format: Guided Discovery.

Prerequisite Fact:
1 nautical mile = 1.15 statute miles

Inform students that the lon/lat system is not an arbitrary system. Instead it can help determine the distance on any local map by using the lines of latitude and longitude. Therefore an experienced navigator does not need to use a distance legend. Ask the students to examine their maps and compare the distance legends with distances between points on the lines of latitude and longitude.
· Does any unit correlate with a specific distance?
· On which axis does it work?
· Why doesn't it work on the other axis?

· 1 nautical mile is equal to 1 minute of latitude, and 60 minutes of latitude equal one degree.
· Lines of longitude do not work because the distances between them are not constant.

To really see why lines of longitude cannot be used as a consistent method of measuring distance, have the students look at a globe or a world map. Look at what happens to the lines of longitude as they approach the North and South Poles. (They shrink and the distances between each pair of lines decrease.)

Ask the students to use their new distance technique to measure how far the ship had traveled on each leg of its course. The ship should have traveled approximately 34 nautical miles which is approximately 39 statute miles.

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