How Do Novice and Expert Learners Represent, Understand, and Discuss Geologic Time

This dissertation examined the representations novice and expert learners constructed for the geologic timescale. Learners engaged in a three-part activity. The purpose was to compare novice learners' representations to those of expert learners. This provided insight into the similarities and differences between their strategies for event ordering, assigning values and scale to the geologic timescale model, as well as their language and practices to complete the model. With a qualitative approach to data analysis informed by an expert-novice theoretical framework grounded in phenomenography, learner responses comprised the data analyzed. These data highlighted learners' metacognitive thoughts that might not otherwise be shared through lectures or laboratory activities. Learners' responses were analyzed using a discourse framework that positioned learners as knowers. Novice and expert learners both excelled at ordering and discussing events before the Phanerozoic, but were challenged with events during the Phanerozoic. Novice learners had difficulty assigning values to events and establishing a scale for their models. Expert learners expressed difficulty with determining a scale because of the size of the model, yet eventually used anchor points and unitized the model to establish a scale. Despite challenges constructing their models, novice learners spoke confidently using claims and few hedging phrases indicating their confidence in statements made. Experts used more hedges than novices, however the hedging comments were made about more complex conceptions. Using both phenomenographic and discourse analysis approaches for analysis foregrounded learners' discussions of how they perceived geologic time and their ways of knowing and doing. This research is intended to enhance the geoscience community's understanding of the ways novice and expert learners think and discuss conceptions of geologic time, including the events and values of time, and the strategies used to determine accuracy of scale. This knowledge will provide a base from which to support geoscience curriculum development at the university level, specifically to design activities that will not only engage and express learners' metacognitive scientific practices, but to encourage their construction of scientific identities and membership in the geoscience community.