```GeoNet 1: Thematic Maps              by Patrice St. Peter

After this lesson, students will be able to:
(Numbers below correspond to the Minnesota State Learner Outcome List in geography.)

2.  Identify and define conventional map symbols.
9.  Read and understand the symbols used on thematic maps  (e.g., find the height of the
ground from a layer-tinted map; interpret simple relief maps; read heights and identify
slopes, hilltops and valley floors).
14.  Describe a distribution  shown on a map in terms of density, directional alignment,
15.  Interpret pictorial, shaded-area, proportional-symbol, isoline, choropleth,
flow-line maps and cartograms.
20.  Explain some of the factors that influence the choice of projections for particular
mapping tasks  (e.g.,  equal-area for population distribution).
21.  List some major sources of geographic data and briefly describe their
characteristics  (e.g.,  aerial photographs,  satellite images,  field surveys,
topographic maps,  census records,  statistical abstracts,  almanacs,  questionnaires).
22.  Identify the major kinds of symbols used by cartographers and describe the kinds
of data these symbols are usually used to depict (e.g., pictorial symbols, graduated
circles and other proportional shapes, dots and other repetitive symbols, nominal
23.  Explain some  ways in which a cartographer can transform data to make it more
useful for a particular purpose  (e.g.,  calculating percentages of a total,  densities
per unit of area,  values per capita,  or other ratios of several kinds of information).
24.  Describe key aspects of the human visual system  and show how some kinds of
optical illusion can affect the way people see maps  (e.g.,  red colors for emphasis,
upper-left focus for important ideas,  weak grays to minimize clutter in background
information).
25.  Identify some  ways in which a cartographer may intentionally or accidentally
mislead a map reader  (e.g.,  colors that a significant fraction of the population cannot
discriminate, projections or symbols that distort in order to persuade).
26.  Outline the basic components of graphic communication.
28.  Classify geographic data into categories for further analysis or graphic display.
This involves selecting criteria for classification and then applying those criteria to
put individual observations into appropriate groups.
30.  Select appropriate charting or graphing techniques for the display of information
about a place [e.g.,  a)  Pie or bar charts to show proportions of various features in a
place; b)  line or bar graphs to show trends through time in a place; c)  bar graphs to
show comparisons of several places; d)  line graphs to show differences from one place
to another; e)  scatter diagrams to show relationships among features in a place; and f)
graphical analyses to identify exceptions to rules about places].
37.  Create a well-designed map layout that includes the title,  scale,  orientation,
and relative location in the surrounding area  (e.g., city, state, country, or globe).

Time Needed:  1-2 class periods, depending on length of student presentations

Overview:  Students will learn the qualities of a good thematic map and critically
analyze a thematic map used in the media.  This is lesson one in a unit of four lessons
that, when used together, comprise a several day unit on cartography.

Objectives:  Students will be able to:
1.  Understand the communication model of map making and reading.
2.  Apply critical thinking skills to decode and deconstruct a thematic map.

Materials:
1.  Transparency of hand out: Communication Model (see Extra Resources)
2.  Map: "Gun Control Gains Prominence" (see Extra Resources)
3.  Map: " Distribution of McDonald's Restaurants in the United States" (see Extra
Resources)
4.  GeoNet Pre-Test (one per student; see Extra Resources)
5.  Maps from newspapers or magazines that illustrate various problems with map
production
6.  Hand out: "Introduction to Thematic Maps" (see Extra Resources)

Preparation:
Gather and prepare materials.

Activities:
1.  Use the handout entitled COMMUNICATION MODEL as an overhead.  Discuss the
sequential steps involved in map making and reading.  Students may want to take notes
or copy any abbreviated notes you select to list on the board. This information is
crucial to cartography!  Students may be required to copy the diagram as you explain
each part.
2.  If your students are not familar with thematic maps, present the information in the
hand out INTRODUCTION TO THEMATIC MAPS.
3.  Give students the GeoNet pre-test.  If you are teaching the entire GeoNet unit, you
may want to give the test again at the end of the unit to gage students improved
understanding of thematic maps.
4.  Divide students into groups of three or four.  Give each group a map to analyze.
Ask each group to study the map and identify two things particularly good about the way
the map was produced and at least two things that are particularly bad about the way
the map was produced.  Each group should select a recorder to write these observations
on paper.	Each group should select a speaker to give his/her group report on the
map they analyzed.  Two maps are enclosed for this activity; however, feel free to use
any thematic maps you may have collected from newspapers, magazines, etc.  Try to use
maps students might see in everyday/ordinary life.
5.  Show a transparency of the map from each group as they give their report.  The
discussions may continue for 3-5 minutes, depending on what each group choses to
highlight as good and bad characteristics of the map.

NOTES TO THE TEACHER:
When students are analyzing the maps for qualitative differences in graphic
presentation, they are using very sophisticated skills which can be applied to
deconstruct or decode a map that a cartographer has encoded.  These skills involve
several modes of communication:  articulacy, numeracy, and graphicacy.  Encourage
critical thinking skills and create healthy criticism of maps, especially maps used in
the media.

Perhaps some of their discussion will include these comments:

1.  Symbols/Symbolization is confusing.
2.  Map is cluttered and therefore, noisy.
3.  Title is not there or is not good.
4.  No source for the data.
5.  Message of map is not clear.
6.  Orientation is confusing.
7.  Date/Year is unkown.
8.  No neatline or border around the map.
9.  Categories in the legend (or Classification Scheme) have skewed the spatial
pattern.  Map may look differently with a different selection of categories.
10.  Too many categories.  Studies have shown that 3-5 categories are best for most