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# Looking for Data Patterns in Weather-Related Primary Sources

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This post was written by Tom Bober, the Library of Congress 2015-16 Audio-Visual Teacher in Residence.

Primary sources often reward close observation with additional information that can lead to deep thinking, questioning, and new understandings. For example, examine the March 17, 1921, photo of a US Weather Bureau weather station, one of several primary sources in the Library’s new Weather Forecasting Primary Source Set. At a glance, it is recognizable as a photo of weather instruments, but a closer look also reveals weather data that can be analyzed to identify repeating patterns and disrupt possible misconceptions.

Ask elementary or middle school students when the hottest part of the day is, and some may tell you it is noon, when the sun is highest in the sky and we see our smallest shadow. Teachers can disrupt this misconception by asking students to track temperature at frequent intervals for a day, but students may wonder if this is true beyond the particular day they recorded the temperature.

Share with students a detail of the thermograph shown in the U.S. Weather Bureau photo, which was taken more than 95 years ago. (You can find the thermograph by downloading the highest resolution image and zooming in to the lower portion of the photo.)

 Detail from Image of U.S. Weather Bureau Instruments. Harris and Ewing Detail from Image of U.S. Weather Bureau Instruments. Harris and Ewing

Ask students:

• What does the image show?
• How is the graph labeled to show time and temperature?
• What do you notice about the tracking of the temperature in the graph?
• According to this data, when is the hottest part of the day? A range of hours may be an appropriate response.

Support students in comparing the data from the image to the data they collected. Focus them first on the hottest part of the day: How closely do they match?

Encourage students to consider whether that pattern is consistent  by looking at additional temperature data. In the same image, above the thermograph, is a record of the temperature from the previous two weeks. Students can examine the graph to look for the same pattern or instances where the pattern does not occur.

Sometimes, scientists may not have historical data that is as complete as the thermograph readings. For example Thomas Jefferson’s weather record, also in the Weather Forecasting Primary Source Set, records multiple readings a day. While there is not enough data each day to look for patterns in daily temperature, the temperature data is recorded over decades and in different geographic locations, allowing for averages to be taken over time and place and different types of patterns to be discovered.

How could your students use other information from the Weather Forecasting Primary Source Set to explore the science of weather?