A SIMPLE MODEL FOR TEACHING STABLE OXYGEN ISOTOPE FRACTIONATION

Understanding the fractionation of stable oxygen isotopes is crucial to understanding how geologists reconstruct past environmental conditions. Unfortunately, the fractionation process occurs on time and space scales that are outside of the frame of reference of most introductory students. However, by building a simple physical model it is possible to put isotope fractionation literally into the palms of students' hands. The supplies to make the model can be purchased for under a dollar per model, and the model is simple enough to assemble that students can build it themselves during class time. For the past two years, I have been using this model in introductory geology classes. I have also collected assessment data on student performance for these two years as well as for the three proceeding years. Assessment data collected from quizzes and exams both indicate that the use of this demonstration in class is improving student understanding of the mechanics of fractionation as well as their applications to environmental geochemistry.