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What's Up With the Weather?

Classroom Activity

Objective
To use a statistical analysis technique, the moving average, to search for meaningful trends in regional raw temperature data.

• copy of the "Temperature Trends" student handouts
  Part I ( HTML)
  Part II ( HTML)
  Temperature Graph ( HTML)
• pencil
• yellow, blue, green, and red pencils, markers, or crayons
• scissors
• tape
• calculator

Part 1

1. Divide the class into 10 groups, one for each year of data.

2. Distribute both Part 1 Temperature Trends and "Temperature Graph" student handouts with the other materials. Ask student to discuss the raw data before graphing.

3. Record their observations on the board.

4. Have each group graph its year of data, using the data Monthly Average Temperatures and chart provided on the Part 1 "Temperature Trends" student handouts. After they have graphed their data year, direct students to cut out their graphs and lightly tape them together temporarily, spanning 1989 to 1998.

5. Display the taped-together graphs on the wall or floor. Have students observe any trends. Add these observations to the initial observations on the board.

Part 2

1. Students will now plot a 12-month moving average. Distribute the Part 2 "Temperature Trends" student handout. You may need to help students with the instructions in this part.

2. Demonstrate the algorithm until students are able to calculate the moving averages on their own. Students will realize they can plot only their first seven averages, June to December, on their own graph. They must plot the next five averages on the next year's group's graph, January to May. The previous year's group will fill in averages for January to May on their graph.

3. The group working on the final year has only enough data to produce one moving average, June.

4. Once students have finished their moving averages, discuss the results with them. What do they see in the data now? How does that differ from what they inferred from the previous plotting technique? What does each plotting technique tell them? What is the value of the moving average?

The graph students create will show temperatures above and below the average temperature line of the chosen data set. The moving average sums for each month are presented below. Plotting for the January sums begins in June. (Note: Strictly speaking, plotting for a moving average would begin at the exact center point of the data set; however, because 12 months is an even number and a 12-month average can't have a "center month," June was chosen as the starting point for plotting the averages.)

12-Month Moving Average for Boston, Jan. 1989 to Dec. 1998*

The visual result of plotting the monthly average temperature with the 12-month moving average temperature line is impressive. The Boston data set provides some tantalizing hints in the monthly plot that some cyclical temperature changes may be occurring, but they turn out to be inconclusive in the moving average trend. A moving average is a sliding average of whatever is being studied. In this activity, the continuous average of a cluster of data (a 10-year span of temperature records) yields more meaningful information about temperature trends than a single data set (a one-year span of monthly temperature records) provides. A single data set is more likely to contain fluctuations that do not appear in a larger trend analysis.

Most students will conclude that there isn't much of significance when looking at results in the moving average trend. Some may argue for a three- to four-year cycle of small change. The data on this graph alone, however, are not compelling as it only shows 10 years of information. Students may suggest that by looking farther back and creating a moving average for the past 100 years they can verify this trend. However, that opens the question about the past being a reliable predictor of the future.

Other uses include analysis of the economy, unemployment, rainfall, pollen, stream flow, sea water temperatures, traffic volume, and dress hemlines.

Books

Global Warming by Jenny Tesar, New York: Facts on File, 1991.
Describes the greenhouse effect, how human activities have impacted global carbon dioxide and ozone levels, and steps that can be taken to slow the rate of global warming and ozone destruction.

The Greenhouse Effect: Life on a Warmer Planet by Rebecca L. Johnson, Minneapolis, Minnesota: Lerner Publications Company, 1990.
Describes the science of how Earth's atmosphere works, identifies gases contributing to global warming and how human activities are causing global climate to change, and offers suggestions on how to help slow the rate of global warming.

Global Warming: Opposing Viewpoints by David Bender and Bruno Leone, ed., San Diego, California: Greenhaven Press, Inc., 1997.
Offers opposing viewpoints about many global warming issues including the causes of global warming, the seriousness of the threat, and possible effects of a changing climate.

Web Sites

NOVA Online—Global Warming
http://www.pbs.org/nova/warm/
Delves deeper into the program's content and themes, with features such as articles, timelines, interviews, interactive activities, resource links, and more. Launch date: Friday, April 14.

U.S. Global Change Research Information Office
http://www.gcrio.org/index.html
Features general information, resources, and links to other organizations dealing with global change. Also includes an e-mail service, Ask Dr. Global Change, where you can send questions about global environmental change.

The "Temperature Trends" activity aligns with the following National Science Education Standards:

Grades 5-8

	Science Standard A: Science as Inquiry

Abilities necessary to do scientific inquiry

• Use appropriate tools and techniques to gather, analyze, and interpret data.

• Use mathematics in all aspects of scientific inquiry.

	Mathematics Standard 10: Statistics

Grades 9-12

	Science Standard A: Science as Inquiry

Abilities necessary to do scientific inquiry

• Use technology and mathematics to improve investigations and communications.

• Formulate and revise scientific explanations and models using logic and evidence.

	Mathematics Standard 10: Statistics