Great Grids
Submitted by: Christine McCoid
Lesson Overview
Concept In this lesson, students see how grids are used for the purpose of accurately scaling down an area.  Students will use a grid to create a scaled down object, and relate the process to map making.
Performance Objectives

Students will be able to:
1.  Understand and use a gridding process.
2.  Use grid boxes as a measurement tool.
3.  Recognize the use of grids in map making. 


1.  Poster-sized graph paper (approx. 2-inch squares)
2.  Small graph paper (approx. 1/2-inch squares or 1-cm squares)
3.  Pencils and rulers


1.  Before lesson, draw two geometric shapes on two poster-sized sheets of graph paper.  Be sure that the shape carefully follows the grid on the paper.

2.  Explain to students that you are going to give them a geometric challenge.  Show the class the first shape you have drawn, and tell them they are to copy it exactly, but they are to use smaller graph paper.  Ask for some suggestions from the class for strategies they may use. 

3.  Give each student a sheet of graph paper, a pencil, and a ruler, and have them copy the shape.  When every student is done, share the shapes as a class and discuss their strategies.

4.  Ideally, one or more students will have used a gridding process.  Have those students explain the process to the class.  If no one has done so, you can explain the process.  Point out to students that the grid boxes can be used as a measuring tool.  Where your shape may have one side that is 6 boxes long, their copy should have one side that is 6 boxes long.  If all of the sides match up in that way, the shape the student has drawn will be an exact replica of your shape, drawn to scale.

5.  Give each student another sheet of graph paper.  Show the class the second shape you have drawn on poster-sized graph paper, and have students copy the shape again using the gridding process you have explained.  When they are done, ask volunteers to share their shapes and explain how they were made.

6.  For additional practice, have half the class draw shapes on poster-sized graph paper, then give each shape to the student in the other half of the class to copy.  Share and discuss the shapes again.

7.  Ask the class, "How can we relate this activity to map making?"  Elicit from students that map makers have to use a similar process to scale down large areas.  Show the class a map which features longitude and latitude lines.  That is the grid used by map makers, and they use the same process of "scaling down" used by the class to draw their shapes.

Teacher Notes  Use this lesson in conjunction with "Cartography Concepts" article.
Student Assessment Tools Visual presentation and Other

Students will be assessed on:
1.  Correct and accurate use of the gridding process.
2.  Class discussion.

Related Web Sites Lewis and Clark Expedition Map:  Library of Congress map from the expedition. Has zoom capability.

The Lewis and Clark Trail:  Links and resources about the expedition.

The History of the Lewis and Clark Expedition:  A detailed history of the expedition.

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