Social
Studies:
Great Circle Route
Summary: Students compare
routes between Minnesota and China using a map and globe. Using the “great
circle route” method,
students find the shortest route between two points.
Minnesota Academic Standards Information
Subject Area Focus: Social Studies - Geography
Educational Level: Teachers may adapt the activity for the
various grade levels. Intermediate, Middle
Middle (6-8) Level
The student will use maps and globes to demonstrate specific and
increasingly complex geographic knowledge.
For the complete standard, see the Minnesota Academic Standards
web site at http://education.state.mn.us/mde/Academic_Excellence/Academic_Standards/index.html
Intermediate (4-5) Level
The student will use maps and globes to demonstrate specific and
increasingly complex geographic knowledge.
For the complete standard, see the Minnesota Academic Standards
web site at http://education.state.mn.us/mde/Academic_Excellence/Academic_Standards/index.html
LEARNING ACTIVITY
Directions
Objectives:
- To be able to locate home community and China on a world
map.
- To understand and use the "great circle route" method
of finding the shortest route between two points on the globe.
- To become familiar with the limitations of a map (vs. a
globe).
Preparation: Prepare black-line maps for students
to draw their routes on. A world map can be found on the National
Geographic’s Xpedition site at http://www.nationalgeographic.com/xpeditions/.
Time Required: 20-40 minutes
Description
Introduction for Students
What does it mean to live on a round planet? One thing is
that distances and routes marked on a flat map may be deceiving.
Any time you put a 3-D globe into a 2-D map, you distort at least
one of the following: distance, direction, size or shape. Most
maps try to preserve three of the four as closely as possible.
- Get out a world map, a globe, and a piece of yarn.
- Have students find Minnesota and China on the world map.
(Don't use a globe yet.) From this map, figure out
what appears to be the straightest, shortest route from one
place to the other. Note what cities and countries
this route passes through. On a blank map, have them
draw the route.
- Using the globe and some yarn, trace a route from Minnesota
to China. Keep the yarn level with your eyes and parallel
to the floor or table. Compare this route to
the one that you found on the map. Ask students to
notice if the two routes pass through similar cities and
countries. The idea is that if they key the yarn level with
their eyes and parallel to the floor or table, they'll probably
follow the lines of latitude. Make sure they measure
the yarn at this point.
- Then challenge students to find a shorter distance between
the two places. Why is this route shorter?
- Discuss the concept of the "great circle." A
great circle is the line traced on the surface of the globe
when a plane slices through the center of the sphere.
- Have students find the "great circle route" from
Minnesota to China. Turn the globe slowly so that the
lines of latitude are no longer parallel to the floor but
so that you can still see both China and Minnesota. Take
the yarn from Minnesota to China again, but this time have
the yarn go over the top of the globe and around back to
Minnesota. You don't have to have the yarn go through
the north pole, just over the top. You have just made
what is known as a "great circle route" which is
used to find the shortest distance between two points on
a globe.
- Using the yarn, note the difference between the length
of this route and the first one that you used, the one level
with the lines of latitude. Discuss why are these
two so different.
- Have students draw the shorter, great circle route on the
blank map and compare it to the first one that they drew. Discuss
how a 2-D map can distort the distance and direction of the
3-D world.
Learning Resources: None
Printable Materials: Prepare black-line maps for
students to draw their routes on. A world map can be found on the
National Geographic’s Xpedition site at http://www.nationalgeographic.com/xpeditions/.
Evidence of Learning: The following product(s)
supply evidence of student learning.
- Maps drawn to show the difference between the two routes.
Special Notes
Technology Integration:
Incorporate technology tools and resources in ways that enhance
and support teaching and learning.
Accommodations
Change the activity to accommodate students with different needs,
knowledge and skills.
- Do this activity together as a class.
- It may be necessary to do this activity more than once
for understanding.
Extensions
Extend students' learning with additional activities.
- Have students look at airplane route maps and note how
all the routes look curved. Discuss why. Airplane route maps
are available from Northwest Airlines at http://www.nwa.com/travel/trave/route/.
- Have students find other great circle routes on the globe
and draw them on the blank world map.
- Find common airplane or shipping routes between the two
places. Discuss why travelers and goods/products go through
those routes.
Sources/Credits : Maloney, E. (1994) Chapman piloting.
New York: Hearst Marine Books.
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