Missing Connections in Student Conceptions of Global Change

Global change in the Earth system is characterized by a variety of different phenomena. These phenomena occur in multiple spheres (lithosphere, atmosphere, hydrosphere, biosphere) and are interrelated across spheres. Patterns in global change are often difficult for students to comprehend and, for this reason, a study was undertaken to determine student conceptions and misconceptions in global change. Students in a university earth science course for non- majors constructed four timelines that represent the four spheres of the earth system. Each event on each of the student's timelines was measured and placed into a categorical database. The data were then analyzed by a variety of statistical measures to determine trends and patterns of student thought. A scientific model was also created as a basis for comparison. The model was created from multiple sources and represents major changes in Earth History, with specific attention to how spheres interact with and relate to one another. Results indicate that student conceptions of global change are largely fragmented, specifically in the context of the lithosphere and biosphere. For instance, 71% (n=113) of students placed a single large continent (often called “Pangeae” by the students) in the first one-fifth of their timeline, and no student placed this object on their timeline more than once. In addition, concepts that are correlated in the scientific model (e.g. high temperatures and high sea level) were not correlated in student models. These results suggest that many alternative conceptions are imbedded into student understanding of earth systems. These alternative conceptions serve as a barrier to learning and must be addressed in order for broader student understanding of global change.