Academic journal article Journal of Geoscience Education

College Student Conceptions of Geological Time and the Disconnect between Ordering and Scale

Academic journal article Journal of Geoscience Education

College Student Conceptions of Geological Time and the Disconnect between Ordering and Scale

Article excerpt


College student conceptions of the scale of geologic time and the relationships between time and geological or biological events were evaluated through interviews, open-ended questionnaires, and student generated timelines collected from four institutions. Our data indicate students hold a number of alternative conceptions about the Earth's formation and the appearance of life, and these ideas are remarkably consistent across institutions. Transferability of these findings was evaluated via comparison with Geoscience Concept Inventory questions related to geologic time collected from 43 institutions nationwide. Detailed evaluation of student timelines reveals a notable disconnect between the relative relationships between the age of the Earth, the time required for the origin of the first life forms (prokaryotes), and the evolution of dinosaurs and humans. Students generally placed these events in the correct relative order, but had a poor understanding of the scale of time between events. Intriguingly, timelines can be mapped onto ternary diagrams, and the relationship between ternary diagram zoning and specific ideas of geologic time is explored. We found that some students, for example those with a young Earth perspective, map onto specific conceptual zones on ternary diagrams.


Student understanding of geologic time has been explored in a variety of settings, including elementary (AuIt, 1982; Schoon, 1992), high school (Marques and Thompson, 1997; Oversby, 1996; Schoon, 1992), college (DeLaughter et al., 1998; Libarkin et al, 2005; Schoon, 1992), pré-service (Gosselin and Macklem-Hurst, 2002) and in-service teacher (Trend, 2001; Dahl et al., 2005) populations. Researchers have focused on both relative (Trend, 1998; Trend, 2000; Trend, 2001; Dodick and Orion, 2003) and absolute time (Libarkin et al, 2005; DeLaughter et al, 1998; Trend, 2001), and some work shows intriguing relationships between relative positioning of geologic events and understanding of absolute geologic time (e.g., Trend, 2001; Dodick and Orion, 2003; Libarkin et al., 2005). Researchers generally find that students are more comfortable with relative time than absolute ages (Trend, 2001), although these same students may have a poor understanding of absolute ages (Libarkin et al., 2005). In addition, young children tend to have a difficult time extracting analogies about relative ages to relative age dating of geologic strata in general (Ault, 1982).

Trend (1998; 2000; 2001) and Dahl et al. (2005) have conducted detailed studies of children, pre-service and in-service educators' ideas about and interest in geologic time. These works employ a similar event-ordering task that requires participants to consider when various events happened in Earth's history, and more specifically, the relative order of geologic events. Events are both biological and physical in nature, and may include the appearance of birds, the opening of the Atlantic Ocean, the appearance of life ana the formation of the planet Earth. In general, participants seem to be familiar with the generalrelative order of biologic events in Earth's history, although geologic events, such as the opening of the Atlantic, do not seem to have a significant place in student or teacher ideas of the Earth through time (Trend, 2001). Trend (2001) suggests that this may be the result of the attention paid to biologic events throughout the K-12 curriculum. In addition, several researchers have observed that participants of all ages, ranging from elementary-aged students to in-service teachers, believe that Earth and life originated at the same time (Marques and Thompson, 1997; Trend, 2001; Libarkin et al., 2005).

In addition to fundamental research into student conceptions, significant energy has been put into considering the difficulties students have understanding geologic time, as well as Grafting curricular materials that can facilitate instruction. …

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