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Why Is Alaska So Cool?
(. . . with all that daylight?)
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Module Overview
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Guiding Questions
When students complete this module, they will infer a provisional answer to the guiding question: Why is Alaska So Cool (with all that daylight)? Alaska summer daylight is considerably longer than places farther south, which reasonably leads one to conclude that temperatures should be warmer in Alaska than elsewhere. Real world experience indicates quite other than this. Answers to the guiding question leads students through two computational science methods: use of a graphing calculator and of a spreadsheet.
What Will Students Do?
Students do not measure temperature directly, but will infer temperature phenomena indirectly from sunlight intensity measurements. Students collect primary data for one variable: sunlight intensity at a given latitude. Sunlight intensity and differences in intensity depend upon several variables. These variables include, but are not limited to, distance from the sun, solar angle, the distance light travels through earth's atmosphere, daylight duration, and atmospheric conditions such as cloudiness or pollution.
Students will collect samples of sunlight intensity at solar noon on the equinox or other target date. After the data have been collected, they will analyze the data and determine the line (or curve) of "best fit" using the TI-83 Plus graphing calculator and an Excel spreadsheet. This graph and its equation serve as a mathematical model that best accounts for the data and from which they may infer a scientifically reasonable answer to the guiding question.
Before actual sunlight data collection, students will have spent time in preparation learning to use the equipment and software, investigating the behavior of light intensity under varying conditions, practicing physical methods to determine solar noon and solar angle, reviewing pertinent mathematics, and in developing preliminary mathematical models from lab-based investigations.
Three Different Implementations
A teacher may choose one of three distinct implementations for collecting sunlight intensity samples. The lesson plans assume the first one. (1) Several schools around the nation may cooperate together and have a target date on which each school collects samples. These samples can then be compared against latitude and other factors. (2) One classroom collects samples hourly throughout a given day beginning in early morning and concluding as late in the day as practicable. The data can then be compared to solar altitude. (3) One classroom collects data over a period of several weeks at solar noon on each of the collection days. The samples may be compared to solar altitude over the progression of the given season of the year.
These lesson plans assume a cooperative venture with several classrooms.
Sequence of Activities
The sequence of activities is found under the Activities menu item to the left. Collection dates are approximate and need to take into account overcast conditions. Therefore, students should perform the Solar Angle experiment as near as possible to the target collection date and should collect sunlight intensity samples on the first clear day within a few days of the target collection date.
Use of the TI-83 Plus graphing calculator is a prerequisite for this module. The lesson plans include a tutorial for the use of the TI-83 Plus graphing calculator at the end of the menu choices to the left.
To gain most fully from the module, it usually is best to follow the activities in the given order. Activity 9 may be started before all data from Activity 8 is compiled from extended sites.
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