Using Latitude and Longitude
Curriculum Links: Grade 6 Social Studies – Dynamic Relationships
Grade 7 Social Studies –Maps
Outcomes:
Students will define "absolute location”, latitude and longitude. They will use the grid system when
working with maps. Locate on a map or globe the Earth's poles, circles, tropics, and beginning
points of measurements for latitude and longitude and use Cardinal and intermediate directions
as well as latitude and longitude to locate places on a map.
Materials:
Atlas, map and worksheet handouts
Explore: Tell the students that together the class will come up with notes to review the concepts of Latitude and
Longitude. This review lesson will help with future studies of GPS technology. Following are some notes the
teacher can refer to in helping the students stay on the correct track.
Any location on Earth is described by two numbers--its latitude and its longitude. If a pilot or a ship's captain
wants to specify position on a map, these are the "coordinates" they would use.
Actually, these are two angles, measured in degrees, "minutes of arc" and "seconds of arc." These are denoted
by the symbols ( °, ', " ) e.g. 35° 43' 9" means an angle of 35 degrees, 43 minutes and 9 seconds (do not confuse
this with the notation (', ") for feet and inches!). A degree contains 60 minutes of arc and a minute contains 60
seconds of arc--and you may omit the words "of arc" where the context makes it absolutely clear that these are not
units of time.
Latitude
On a globe of the Earth, lines of latitude are circles of different size. The longest is the equator, whose latitude is
zero, while at the poles--at latitudes 90° north and 90° south (or -90°) the circles shrink to a point.
(The diagram should be drawn on the whiteboard to show visual representation.)
Longitude
On the globe, lines of constant longitude ("meridians") extend from pole to pole, like the segment boundaries on a
peeled orange.
Every meridian must cross the equator. Since the equator is a circle, we can divide it--like any circle--into 360
degrees, and the longitude φ of a point is then the marked value of that division where its meridian meets the
equator.
(Again draw on the white board this simple diagram)
What that value is depends of course on where we begin to count--on where zero longitude is. For historical
reasons, the meridian passing the old Royal Astronomical Observatory in Greenwich, England, is the one chosen as
zero longitude. Located at the eastern edge of London, the British capital, the observatory is now a public museum
and a brass band stretching across its yard marks the "prime meridian." Tourists often get photographed as they
straddle it--one foot in the eastern hemisphere of the Earth, the other in the western hemisphere.
If we put both the latitude lines and the longitude lines together on the sphere, what've we got? A GRID! Now we
can locate places by giving their latitude and longitude.
All these notations allow us to locate places on the Earth quite precisely – to within inches. A degree of latitude is
approximately 69 miles, and a minute of latitude is approximately 1.15 miles. A second of latitude is
approximately 0.02 miles, or just over 100 feet.
Activity:
Have the students quickly complete these two simple worksheets to ensure everyone understands how to read
latitude and longitude off of simple maps.
Practice by filling in what degrees are being asked for by these blank lines and arrows.
Start on this left side and fill in these blank lines the arrows point to.
90º N
180º W
45º N
135º W
0º Latitude
90º W
45º S
45º W
90º S
0º Longitude
These are the points to fill in on the above map.
45º E
90º E
135º E
180º E
Discuss in class and have students write in their notebooks the meaning of the following terms:
absolute location
Antarctic Circle
Arctic Circle
Cardinal directions
Equator
grid
Tropic of Cancer
intermediate directions
International Date Line
relative location
location
longitude
meridian
Tropic of Capricorn
parallels
Prime Meridian
latitude
scale
South Pole
hemisphere
North Pole
Follow up the definitions by asking the students to answer these questions and do the activity:
1. Why is it important to be able to measure the Earth using latitude and longitude?
2. In what types of situations might it be helpful for you to know your latitude and longitude?
3. Using an atlas and maps students will:
a.) practice locating places on a map using latitude and longitude
b.) list the latitude and longitude of various locations on a map
Closure: This class we explored the concept of how we find geographical positions using latitude and longitude
from maps. The new technology of GPS, Global Positioning Systems is based on knowing how to put in specific
points using latitude and longitude. Before exploring the GPS tools it was important to review the basics of
pinpointing places on our planet.