Modeling Convection

Autor/inn/en	Ebert, James R.; Elliott, Nancy A.; Hurteau, Laura; Schulz, Amanda
Titel	Modeling Convection
Quelle	In: Science Teacher, 71 (2004) 7, S.48-50 (3 Seiten) PDF als Volltext Verfügbarkeit
Sprache	englisch
Dokumenttyp	gedruckt; online; Zeitschriftenaufsatz
ISSN	0036-8555
Schlagwörter	Water; Plate Tectonics; Science Instruction; Models; Secondary School Science; High School Students; Thermodynamics; Science Experiments; Ventilation; Science Process Skills; Heat; Motion; Color; Scientific Concepts + Suchen Sie Ihr Suchwort? Wasser; Plattentektonik; Teaching of science; Science education; Natural sciences Lessons; Naturwissenschaftlicher Unterricht; Analogiemodell; High school; High schools; Student; Students; Oberschule; Schüler; Schülerin; Studentin; Thermodynamik; Hitze; Bewegungsablauf; Colour; Farbbezeichnung; Farbe
Abstract	Students must understand the fundamental process of convection before they can grasp a wide variety of Earth processes, many of which may seem abstract because of the scales on which they operate. Presentation of a very visual, concrete model prior to instruction on these topics may facilitate students' understanding of processes that are largely invisible (atmospheric convection) or that operate on large spatial and temporal scales (mantle convection and plate tectonics). Typically, teachers use simple models that employ differences in temperature and density to help students visualize convection. However, most of these models are incomplete or merely hint at (instead of model) convective circulation. For example, teachers commonly model convection by introducing heated or cooled dyed water to a container of room-temperature water. When hot water (red) is introduced to the bottom of the container, the tinted, less dense water rises. Cold, dyed water (blue) is poured along the side of the container and students observe that the colored water sinks and flows along the bottom. These traditional models suffer from three fundamental shortcomings. First, movement stops when the introduced fluids mix or density equilibrium is attained. Second, the markers used (typically food coloring) disperse in the fluid of the larger container, which makes the motion difficult to follow. Third, these models illustrate only a portion of a single convection cell, whereas in nature, convection typically occurs in multiple, complete cells (e.g., global wind patterns, thunderstorms, and mantle circulation associated with plate tectonics). Although the ease of the traditional, food-coloring models is appealing to teachers, students who observe these demonstrations may develop simplistic or incomplete conceptualizations of convection. This article discusses how these shortcomings are resolved by using an alternative system of fluid and markers in a simple, low-cost apparatus that not only maintains dynamic convective circulation, but also illustrates two adjacent cells. (Contains 4 figures.) (ERIC).
Anmerkungen	National Science Teachers Association. 1840 Wilson Boulevard, Arlington, VA 22201-3000. Tel: 800-722-6782; Fax: 703-243-3924; e-mail: membership@nsta.org; Web site: http://www.nsta.org
Erfasst von	ERIC (Education Resources Information Center), Washington, DC
Update	2017/4/10