Great-circle routes: why flight paths curve on a flat map, grades 6–8
What it is: a globe activity for grades 6–8 where students stretch a string between two cities on a globe to find the shortest route, called a great-circle route, then copy that route onto a flat map. A route from New York to Tokyo, for example, runs far to the north, near Alaska, which looks strange on a flat map but is shorter on the round Earth.
Time: about 25 minutes. Grade: 6th to 8th grade.
Materials: a globe, string, tape, a flat world map (Mercator works best for showing the curve), and a list of city pairs: New York and Tokyo, Los Angeles and London, Chicago and Beijing, Miami and Madrid.
- Ask: "On a flat map, what is the shortest path from New York to Tokyo?" Students draw a straight line on the flat map.
- On the globe, tape one end of the string on New York and pull it tight to Tokyo. Note which places it passes over.
- Students mark 4 or 5 points under the string and plot those points on the flat map, then connect them.
- Compare: the globe route looks curved on the flat map but is shorter. Explain that a great circle divides the Earth into two equal halves, like the equator, and its arc is the shortest path between two points on a sphere.
- Groups repeat with the other city pairs and describe each route.
- Discuss why airplanes and ships often follow these routes when weather and rules allow.
Differentiation: students who need support do one city pair with a partner. Students who are ready explain why routes between cities on the equator follow the equator itself. English learners can use the words route, curve, shortest and sphere.
Quick check: ask a student why a straight line on a Mercator map is usually not the shortest route.
Save this activity to your library so it is ready when you need it.
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About this resource
- Shared by
- @UpOnlyLearning · Curriculum team
- Posted
- Oct 31, 2026
- Type
- Lesson plan
- Grade
- Grades 6–8
- Subject
- Social studies
- Language
- English
- License
- Free for classroom, co-op and tutoring use. Please don't resell.