Academic journal article Journal of Geoscience Education

Changes in Geologic Time Understanding in a Class for Preservice Teachers

Academic journal article Journal of Geoscience Education

Changes in Geologic Time Understanding in a Class for Preservice Teachers

Article excerpt


The paradigm of geologic time is built on complex concepts, and students master it in multiple steps. Concepts in Geology is an inquiry-based geology class for preservice teachers at Wright State University. The instructors used the Geoscience Concept Inventory (GCI) to determine if students' understanding of key ideas about geologic time and Earth history changed between the first and last day of the course. For three of the four GCI questions analyzed in this study, the number of correct student responses increased significantly between the pretest and the post-test, indicating that many of the students were learning the concepts being tested. Our analyses indicates that for two of the GCI questions, certain incorrect pretest choices were more likely to give way to correct post-test answers than others. For example, on a question about timelines, students who chose the answer that gave a correct order of events (incorrectly scaled) on the pretest were more likely to switch to the correct answer on the post-test than students who chose an answer with both an incorrect order and scale on the pretest. These results imply that some misconceptions are more likely than others to grow into a correct understanding. Misconceptions that consist of multiple incorrect ideas may require more time and effort to replace than simpler ones. © 2011 National Association of Geoscience Teachers. [DOI: 10.5408/1.3604829]


Modern elementary- and middle-school students are preparing to live in a world of environmental changes including global warming, resource depletion, and extinctions. Earth history is essential for understanding these changes and their ramifications. The idea of continental drift, specifically the reconstruction of Pangea, was essential to the development of the modern understanding of plate tectonics. Similarly, fossils were vital to the development of the theory of evolution, the foundation of modern biology. However, studies of in-service K-8 teachers indicate that they seldom possess adequate content knowledge needed to teach Earth history and geologic time and that they are not confident about teaching these subjects (Trend, 2001; Dahl et ah, 2005), which makes it likely that they will avoid teaching them.

At Wright State University, all preservice K-8 teachers take a required ten-week course, Concepts in Geology. The instructors used pre- and post-testing to learn more about their students' initial understanding of Earth history and geologic time when they enter the class, and to determine how and if the course changes that understanding. In order for students to release their hold on their misconceptions, they must abandon or modify older paradigms when confronted with a new model that does not fit with their current mental model (Taber, 2001; Çakir, 2008).

Ideas about the physical Earth that conflict with modern scientific understanding are described as "misconceptions" rather than "alternative conceptions" in this context. The purpose of this study is to help teachers of geology identify and address gaps in their students' knowledge. When students have tried to bridge those gaps using outdated, incomplete, or inappropriate information, then those students have developed misconceptions, which are likely to be expressed through incorrect answers on assessments. The phrase "alternative conceptions" implies that all ideas that students hold about scientific phenomena are valid, whether or not they have any basis in observable reatity. In a classroom setting, "alternative conceptions" may be appropriate for rival scientific theories which are currently supported by scientific evidence. On the other hand, "misconceptions" is more fitting for unsupported ideas, such as dinosaurs co-existing with humans or radiocarbon dating being used to establish the age of the Earth. Misconceptions are ideas that instructors help students to dismantle and replace with more scientificaUy accurate models. …

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