National Teachers Enhancement Network: Lesson Plan

Lesson Plan: Generate an Accurate Landscape Profile from a Topographic Map
Subject: Earth and Space/ Topographic Maps/ Contour Profiles
Classtime: 50 minutes
Grade Level: 6-12

Materials/Technology:

topographic map of study area
paper, pencil, and ruler
Index cards
graph paper
calculator
clear adhesive tape

Safety, Handling, Disposal: None

Learner Outcomes: Students should be able to:

Generate an accurate landscape profile from a topographic map.
Determine the correct interval needed to accurately graph the change in elevation on a single piece of graph paper.
Accurately transpose map scale elevations and distances from a map to profile paper.
Use contour intervals on a topographic map to determine shape of the land represented.

Problem/Purpose:

This activity enables the student to transpose contour lines from a topographic map, generating a topographic profile. A topographic profile is an accurate representation of the shape of the countryside. This gives a visual cross section of the terrain.

Background/ Inquiry:

One of the functions of topographic maps is to accurately represent the terrain of a specific location. Using contour lines, changes in elevation can be very useful in determining the "shape" of the land along a straight line drawn on a topographic map. This straight line would represent a hiking or walking path. The shape of valleys, ridges, cliffs, etc. become obvious to the user of a topographic map when a topographic profile is generated. With practice, the topographic map user will be able to accurately imagine the terrain encountered along a specific path across a topographic map.

Vocabulary List: Here.

Hypothesis:

This is not an experiment; it is a technique or procedure, so no real hypothesis is needed. However, an example hypothesis might be: It is possible to "see" the shape of the land represented on a section of a topographic map by generating a change in elevation profile.

Procedure:

Obtain a topographic map from the teacher.
Take an index card and (just below the SCALE on the map) place it on the Miles scale.
Put a small pencil mark on the edge of the card at the zero and the one-mile mark.
Place this on the topographic map where the profile is to be generated.
Put the "zero" mark on a dark contour line (one with an elevation listed on it) and note the elevation of this line on the card by the zero mark (write vertically).
Using a very sharp pencil, lightly make a line on the map that represents the mile interval from the index card. This line will help keep track of the exact location of the profile being generated.
Use your imagination to generate a sketch of the shape of the land along the line on the topographic map. Hint: If you could take a magic sword and slice the earth along this line, what would the top edge of the cut look like? Keep this sketch to compare with the actual profile.
With the edge of the card along the line you have drawn on the map, make a short vertical mark on the index card where each contour line comes in contact with (disappears beneath) the index card. Be careful to make small light marks on the card exactly where the intersection of contour line and card take place.
Where each dark contour line intersects the card, make the vertical line on the card longer and label it with the elevation of that line from the map.
Continue to do this until all contours within the mile represented have been transferred to the card.
Note the highest and lowest elevation of the mile on the bottom of the card.
Subtract the lowest from the highest. This is the change in elevation taking place within the mile you are studying. Place this result on the card.
On a clean piece of graph paper, use the ruler to construct the two legs of a large right triangle (the X,Y coordinate axis).
Count the number of squares on the Y axis. Divide the change in elevation by the number of squares on the Y axis. If the result is not a whole number, round up so it is a whole number. This is the value of the equal intervals needed to represent the change of elevation on the Y axis of the topographic profile
Place the elevation intervals on the Y axis. The lowest elevation is at the intersection of the X and Y axis.
Label the Y axis "Elevation in Feet".
Label the X axis "Distance in Miles".
Place the index card so the zero point of the card is on the Y axis and the edge of the card is on the X axis. Use small pieces of tape to secure.
Use ruler as a guide to make marks on the graph paper representing the elevations. Make a small dot with the sharp pencil directly above the mark on the index card at the correct elevation on the graph paper.
Repeat this procedure, making sure the ruler is exactly parallel to the Y axis.
Connect the dots on the paper using a smooth line. This is the shape of the terrain and the change in elevation a person would encounter walking along the mile path indicated by the line drawn on the topographic map.

Results/Analysis:

The rough sketch should be stapled to the topographic profile so students can compare the two. Profiles of the areas of study need to be accurate in the elevation change represented on the map. Profiles must also be accurate in the distance along which the elevation change takes place. The "correct" profile should be available for students to compare to their own work.

Conclusions:

The change in elevation represented on a topographic map can be used to generate an accurate profile of the landscape in question.

Assessments:

What does a contour line on a topographic map represent?
Where is the contour interval located on a topographic map?
Show the students a profile generated by the teacher. Students should be able to state whether the contour lines are close together or far apart.
What would change in the appearance of a profile if one altered the interval of the Y axis, but did not change the actual length represented on the map?
Why do all intervals on the same axis have to be equal?
Have students determine stream flow direction from a topographic map.

Integration: Mathematics (scales, ratios).

Reflections:
Share your thoughts on this lesson with the NTEN team.

Please send an e-mail to Patti Harrison.

Extensions:

Have students choose locations for human habitation (subdivisions etc.) based on a profile generated from a topographic map.
Students choose easiest route for a hiking path based on topographic profile alone.

References/Resources: N/A

Credits
Contributing Teacher: Don Samuelson
NTEN Course: N/A
Instructor: N/A
Developing Team:
T.L. Buck Buchanan, Patti Harrison, Don Samuelson, John Usher, Don Wilson
HTML Programmers: Tyson N. Trebesch, Ryan Huddleston, Andy Tomascak, Ching-Kwong Chia

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