From the beginning I have sought to write a unit which is both exciting for my students, but yet has practical application in the curriculum we now teach. Presently, the "changing earth" is part of the K-4 science curriculum set up by the City of New Haven. Usually this includes discussion of weather, tides, the effect of the moon, and some discussion of earthquakes, volcanoes, and plate tectonics. Earlier I had considered centering the unit on volcanoes, and earthquakes. I guess it is the dramatic view of lava from a volcano, and the sight of buildings falling and the ground splitting that accounts for students' continued fascination with these kinds of events. It is because of this fascination which I have witnessed with my own students that I had chosen to center my unit on these particular types of disasters. However, another consideration - that of relevancy to my students kept nagging at me. As the testing of students broadens it will very shortly encompass both science and social studies. It therefore became apparent that the unit should embrace some scientific knowledge which would be age appropriate to my third graders. They and I have seen the cliché volcano made with baking soda. I hope that the unit is more than just a bag of science tricks. It was my good fortune that the seminar leader suggested that the concept of convection, that is the rising and falling of material due to heat, is at the core of not only volcanoes, earthquakes, and plate tectonics, but also has relevance when speaking of hurricanes, tornadoes, the earth's winds, and other processes. If students could grasp this one principle they would be able to better understand and connect these earthly occurrences under the concept of convection.
In dealing with the wide range of disasters that are included within the unit I suggest that each could be viewed as an independent subtopic and could be taught independently. This would allow for the teaching of the unit at various times throughout the year since at present the time allowed for science is not consistent. A discussion of various disasters could be strung out throughout the school year and yet have some continuity.
The outline of the unit is as follows:
I. Heating and Cooling Basics
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A. How does the application of heat affect materials?
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B. What is convection?
II. The Interior of the Earth
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A. What is the internal structure of the Earth?
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B. What is the source of heating inside the Earth?
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C. What is plate tectonics?
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D. How does convection lead to Earthquakes?
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E. How does convection lead to Volcanoes?
III. The Exterior of the Earth
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A. How do heat and water power convection?
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B. How does convection cause our weather?
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C. How do thunderstorms, hurricanes and tornadoes develop?
