• Color maps of Charleston, Berkeley, Dorchester County regions from 1973, 1994, and 2030 (included; generated by the South Carolina Coastal Conservation League); 1 color set per student team; http://www.charleston.net/org/greenbelt/   (Maps of counties in other parts of the state showing population densities can be found at the Strom Thurmond Institute website located at; http://www.strom.clemson.edu Look at the links listed on the left of the homepage and click on "FASTmap" to bring up maps. Other information on South Carolina GIS maps can be found at www.esri.com or www.intergraph.com/schools.
• Paper hole punches from two different colors of paper; approximately 100 small paper circles or each color per student team (you can also use two different colors of M&Ms, or any other small circular item of consistent size as marking objects)

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Procedure

1. Tell students that they will be examining aerial photographs to compare how much land was developed by humans in 1973 and 1994 in Charleston, South Carolina to the amount of land that is expected to be developed by humans in the year 2030 in the same area. If you develop maps of different areas in South Carolina, use those. Pass out copies of the aerial photographs.
2. Explain the color code found on the photographs. 
       Red = urban area 
       Dark black = highways, Interstates
3. If you are using one of the coastal maps or a map that contains Lake Moultrie, explain to students where water and land boundaries exist.
4. Using the map from 1973, ask students to cover the red portions of the map using one color of marking object (paper circles, M & M's, etc.) and to cover the portions of the map that are not red with the other color of marking object. Using markers of two different colors will help students to explore the concepts of ratio and proportion using concrete models.
5. Ask students to count how many marking objects it took to cover the red portions of the map and to count how many marking objects it took to cover the non-red portions of the map.
6. Ask students to record these numbers on the data sheet provided and to also record the total number of marking objects (of both colors) it took to cover all of the land on the map.
7. Ask students to repeat steps four through six for the 1994 map and the 2030 map.
8. Depending on grade-level, students should generate fractions and /or decimals that symbolically represent their observations (i.e. in 2030 it took 40 red M&Ms to cover the red area and 80 brown M&Ms to cover the non-red areas; 120 M&Ms total were used; 40/120 or one-third of the entire area was urban area)
9. Facilitate a discussion about what they observed. How did the proportion of urban area to non-urban area change over time? What ecological implications might an increase in urban area have? How will the increasing size of human communities affect wildlife communities?

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Activity variation for advanced students

1. Ask students to record the number of marking objects it takes to completely cover all of the land on the map from 1973.
2. Tell students to remove all of the marking objects from the map.
3. Ask students to determine how many marking objects it takes to cover the red area on the 1973 map and to record their findings.
4. Repeat step number three for the 1994 map and the 2030 map. This is a less visual way for students to explore the concepts of ratio and proportion, but is completely sufficient for those students who have a complete grasp of these concepts.
5. Facilitate a discussion about what they observed. How did the proportion of urban area to non-urban area change over time? What ecological implications might an increase in urban area have?

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Follow-up questions 

• What do you think traffic might be like when you are an adult? 
• What kind of wildlife is seen in cities and suburbs? How do you think the wildlife community in a forested area will change if all of the land is developed? 
• When is preserving nature more important than development of a town? When is development of a town more important than preserving nature? What do you think?
• Do you think water and air pollution will increase or decrease over the next thirty years?