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Map Projections: The Grapefruit Activity

Subjects

• Science
--Physical Science
----Earth Science
• Social Studies
-- Geography

• 6-8
• 9-12

Brief Description

A fun hands-on activity makes clear the purposes of different map projections.

Objectives

Students

• understand why we have different types of map projections.

Keywords

map, geography, projection, Mercator, Robinson map, globe

Materials Needed

• grapefruit (one per student or pair of students); an orange could be used in place of the grapefruit
• a knife for cutting into the grapefruit and removing its skin
• permanent black marker

Lesson Plan

Students might complete this lesson in pairs.

In a Christian Scienc Monitor article, How Can We Fix the World If We Can't Read a Map?, David J. Smith, author of If the World Were a Village and Mapping the World by Heart, presents a simple activity for introducing students to the concept of map projections.

To paraphrase the article, here is the "grapefruit lesson" idea that Smith shared:

• Provide each students with a grapefruit.
• Challenge students to think of the grapefruit as Earth.
• Identify and mark on the grapefruit the locations of the North Pole and South Pole.
• Then locate the spot that is halfway between the two poles and use a marker to draw a line around the Earth at that point, which geographers refer to as the equator.
• Draw a few lines of longitude on the map.
• Then draw shapes to represent the continents on Earth.
• Use a knife to pierce the skin of the grapefruit, then use your fingers to get under the skin to peel it off the grapefruit. Try to keep as much of the "globe" intact as possible.

Next, challenge students to create from the sphere (grapefruit) a map that is flat and readable. Alas, as students attempt to create their flat, readable maps they come to understand the difficulty that geographers have in creating an accurate flat representation of Earth. There are many map projections of Earth and none of them is a totally accurate depiction of Earth; each of them is distorted in some way. You and your students can explore some of the many map projections at Map Projections, a resource from the U.S. Geological Survey.

More Resources
See these online resources for more detail or information about presenting this lesson.

Round Earth, Flat Maps
An excellent tutorial from National Geographic.

Map Projection Overview
An overview from Peter H. Dana, department of geography, University of Texas (Austin).

Map Projections
A National Geographic lesson plan for grades 6-12.

Map Projections and Careers in Geography
Another lesson from National Geographic. (Grades 9-12)

Mapping Mars
A middle school lesson plan from National Geographic.

Assessment

Have students write in their journals a reflective response about what they learned from this lesson. Check for understanding of the concepts taught.

Lesson Plan Source

EducationWorld.com

Submitted By

Gary Hopkins

National Standards

SCIENCE
NS.5-8.4 Earth and Space Science
NS.9-12.4 Earth and Space Science

SOCIAL SCIENCES: Geography
NSS-G.K-12.1 The World in Spatial Terms

See more Lesson Plans of the Day in our Lesson Plan of the Day Archive. (There you can search for lessons by subject too.) For additional social studies lesson plans, see these Education World resources:

• Lesson Planning: Social Studies
• Social Studies Subject Center
• Teacher-Submitted Lesson Plans: Social Studies
• Geography A to Z
• Where in the World Is Mrs. Waffenschmidt?
• Mystery State
• Work Sheets from Teacher Created Materials: Social Studies

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