Schmahl Science Workshops: Contour Maps

4월 08 2014

Source: belssw

Summary Information

Keywords:

contours, topo, topography, topographic maps, contour maps, maps

Topic:

Earth Science

Measurement

Target Grade (Ages):

Grade 5 (Ages 10-11)

Estimated Time Required:

1-2 hours

Diversity Indicators:

Grade 5

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LESSON

Goals and Prerequisites

Goals:

Students will be able to:

examine a topographic map and picture the physical landscape represented by it
demonstrate the different elevations shown on a two dimensional topographic map, students build a 3-dimensional model

Prerequisites:

None

Instructional Objective(s)

Students will understand the following concepts:

Many different types of maps exist; each conveys different information
Topographic maps depict the shape of the land
Topographic maps have multiple uses
All topographic maps include common informational features (title, scale, date, location, north, colors and symbols, etc.)
Contour lines connect points of equal elevation
Understand how contour lines are used to represent a three dimensional landform on a two dimensional map
Define contour interval and relief
Understand that different contour intervals are used, depending on the local relief
Know the "rule of V’s"
Know how depressions are indicated on maps
Understand difference between relief and elevation
Calculate a slope
Create 2D contour maps from 3D landforms
Verbally describe landscape depicted on topographic maps
Human construction must accommodate the landscape.
Apply knowledge of interpreting topographic maps to planning hiking expeditions

Instructional Resources

Background:

Topographic maps are used extensively by a variety of people including geologists, field biologists, and hikers. A topographic map is the representation, on a flat surface, of part of the Earth's surface drawn to scale.

Relief is the difference in elevation between any two points. Where relief is low, the area appears to be relatively flat as in river valleys or broad, flat uplands. When relief is high, the area is steep, as in rugged mountainous terrain. Relief determines the contour interval, which is the differences in elevation between adjacent contour lines. A contour line is an imaginary line on the Earth's surface connecting points of the same elevation. Contours can be large for rugged terrain (80 or 100 feet) or they may be small in areas of low relief (10-20 feet). Contour intervals are consistent for a given map, though they may change from map to map. Usually every fifth contour line (an index contour) is printed heavier than the others and bears the elevation above sea level.

In addition to contour lines, heights of many points occur on the map, such as road intersections, summits of hills, lake shorelines, etc. These are spot elevations and are accurate to within the nearest foot or meter. More precisely located and more accurate in elevation are bench marks, points marked by brass plates fixed permanently on the ground. On a topographic map, bench marks are represented by crosses and the elevation, preceded by the letters "BM", is printed in black on the map.

Vocabulary

bench marks - precisely located points of elevation marked by brass plates fixed permanently to the ground. On a topographic map, bench marks are represented by crosses and the elevation, preceded by the letters BM, is printed in black on the map.
contour interval - the difference in elevation between adjacent contour lines on a map.
contour line - an imaginary line on the Earth's surface connecting points of the same elevation.
index contour - on a topographic map, a contour that is printed heavier than others and is usually labeled with the elevation it represents. Index contours occur at regular intervals, often every fifth or every fourth contour line (depending on the contour interval).
relief - the difference in elevation between any two points.
scale - expresses the relationship between distance on the map and the true distance on the Earth's surface.
spot elevations - elevations of road intersections, summits of hills, lake shorelines, etc. These are accurate to within the nearest foot or meter.
topographic map - the representation on a flat surface of part of the Earth's surface drawn to scale. Most topographic maps also show land boundaries and other man-made features.

Materials:

Activity 1: Topography Map Review

Materials:

Topographic maps showing a variety of landforms, with scale of1:24,000. Suggested coverage:
Rounded mountains
Angular mountains
Metropolitan area plus adjacent map
Alluvial fan
Topographic maps of national and state parks, and/or surrounding areas.

Activity 2: Creating A Topographic Map

Materials:

Plastic Landform Model
Acrylic sheet—enough to cover opening of each landform model
One roll of aluminum foil
Rulers
Large beakers or two liter bottles (one or more)

Procedure:

Getting Connected: What do the Students Know?

Ask what types of maps students have seen or used before. Record list on overhead or board, which may include:

Road maps, political maps, weather maps, explorer maps, regional climate maps, etc.

Sharing the Wealth of Knowledge

The Big Idea

Discuss with students why there are so many different types of maps

Different maps convey different information
Only so much information can be conveyed on one map
Discuss what topography and topographic maps are

See what students know or can deduce, before providing answers. Give Greek roots: topo means "place," graphos means "drawn or written":

Topography means the shape of the land
A topographic map is a two dimensional representation of the three-dimensional world

Discuss uses of topographic maps:

Choosing a location for a new airport, school, shopping center, landfill,
Planning a hiking trip
Selecting a route for a new road

Making it Happen

Activity 1: Topography Map Review

Procedures:

Have students look at different topographic maps in groups of 2-4 and identify common features. Discuss the purpose or necessity of each feature, and point out ones that students miss.

Title
Colors and symbols
Legend
Date
Location indicators (picture key, latitude and longitude)
North arrows (geographic and magnetic)
Scale bars (usually given in metric and English units)
Map scale as representative fraction
Contour lines (hold off discussion of these)
1. Recall students attention to board and regenerate list of common features and purpose of each feature.
2. Define contour line as:
  - Line of equal elevation
  - The way topographic maps depict the shape of the land

Activity 2: Creating A Topographic Map

Procedures:

Tape rulers to outside of aquarium at opposite ends of one side.
Fill up aquarium with water one centimeter at a time.
For each new water level, place the acrylic sheet on top of the aquarium and have a different student draw the outline of the waterline on the plastic landforms with an overhead marker.
As activity progresses, discuss terms contour interval and relief with students.
Ask if area outside could be mapped with same contour interval as plastic landforms.
When contours are finished, label every other one (or every third, `etc.) and explain idea of index contours. Point out deflection of contours when crossing a stream bed and explain "rule of V’s." Point out that without labels, depressions and hills look the same, and explain use of hachure marks.

Wrapping It Up: What did the students Learn?

Students will be divided into groups of two, which will each be given a map. Students are to analyze the map and describe the physical characteristics of the area.

Student groups will display maps to rest of class and describe what the area looks like. Verbal reports should include the contour interval for the map and the average relief of hills found on the map.

Instructor will ask critical questions of the class to get students thinking about how human construction (towns, roads) must accommodate the landscape.

Ask Students: How can a two dimensional map represent three dimensions of space?

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