Alternative Conceptions of Plate Tectonics Held by Nonscience Undergraduates

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ABSTRACT

The theory of plate tectonics is the conceptual model through which most dynamic processes on Earth are understood. A solid understanding of the basic tenets of this theory is crucial in developing a scientifically literate public and future geoscientists. The size of plates and scale of tectonic processes are inherently unobservable, necessitating the use of images and models in instruction. To explore plate tectonics conceptions held by undergraduates, we designed and administered a postinstruction survey instrument centered on a common schematic representation of plate tectonics. We report results from a sample of n = 60 nongeoscience majors enrolled in five different introductory Earth-science courses taught at a major research university and a community college. Students held a number of alternative conceptions associated with terminology, plate motion, and plate-related subsurface melting. We also note that some aspects of figures commonly used to teach plate tectonics are problematic for students and may actually result in reinforcement of alternative conceptions. Further work at both the K-12 and college levels directed at innovative approaches to address student conceptions regarding plate tectonics, including designing images that support key scientific messages, is needed. This research can inform curriculum development for entry-level geoscience courses as well as the use of images to convey complex science. © 2011 National Association of Geoscience Teachers. [DOI: 10.5408/1.3651696]

INTRODUCTION

The theory of plate tectonics, which describes the largescale movements and interactions of Earth's fragmented lithosphère, is arguably the most fundamental concept in the geosciences. Studies of the sea floor in the 1950s and 1960s (Dietz, 1961; Hess, 1962; Vine and Matthews, 1963; Morley and Larochelle, 1964) elucidated a mechanism to explain Wegener's drifting continents (Wegener, 1966), paving the way for the scientific revolution that rocked the geological community. The theory of plate tectonics has become so fundamental to understanding Earth that, like the theory of evolution, it is an essential theory for the development of a scientifically literate populace. This importance is reflected in the prevalence of plate tectonics and related processes within K-12 and general literacy standards (AAAS, American Association for the Advancement of Science, 1993; Earth Science Literacy Initiative, 2009). Similarly, chapter headings in introductory-level geoscience textbooks, such as: "Plate Tectonics: A Unifying Theory" (Monroe et al, 2007), "The Way the Earth Works: Plate Tectonics" (Marshak, 2008), and "Plate Tectonics: The Unifying Theory" (Grotzinger and Jordan, 2010) are indicative of the importance of teaching this theory to students enrolled in entry-level geoscience courses.

Earth science courses for nonscience majors or beginning geoscientists generally provide broad overviews of significant scientific concepts, models, and theories. Students who may be taking their only college-level science course will have few, if any, future opportunities to correct their alternative conceptions about scientific models. At the same time, science instruction in introductory courses lays the foundation upon which budding geoscientists will build conceptual models in subsequent courses.

Alternative conceptions have been documented in a number of previous studies on student understanding of plate tectonics and related aspects of Earth. Added to this, concerns have been raised regarding the perpetuation of alternative concepts in Earth science textbooks (Stern, 1998; King, 2010). An understanding of the fundamental nature of Earth's interior is an important prerequisite to grasping plate tectonic processes and their relation to the solid Earth. For example, DeLaughter et al (1998) reported that, prior to instruction, university students enrolled in an introductory-level Earth science course held the alternative conception that a magma layer exists inside Earth. …