Stable isotopes are used throughout earth and environmental science, and students may be exposed to isotope concepts in multiple undergraduate courses. However, students may struggle to correctly interpret isotope ratios and few students understand how isotope measurements are made. New laser-based technologies lower the barrier to entry for giving students hands on experience with isotope measurements and data analysis. We hypothesized that integrating such activities into the curriculum would increase student content knowledge, perceptions, and motivation to learn. The goals for the research were to (1) understand the effectiveness of hands-on experiences and data analysis on student content knowledge, perceptions and motivation and (2) develop and disseminate adaptable materials for teaching stable isotopes.

Two isotope-focused activities and associated teaching materials were developed and tested. The first activity is appropriate for an environmental geochemistry, sedimentology and stratigraphy, or paleoclimate class, and it focused on the concept of Rayleigh distillation. In this activity, students used distillation apparatuses to produce varying fractions of initial reservoir and condensate waters. Water samples were then analyzed on a laser spectrometer and isotope data were used to calculate fractionation factors, which were compared to the literature and conceptually related to a model of ocean water and ice sheets during glacial time periods. The second activity was appropriate for a hydrology or watershed science class, and it focused on the use of stable isotopes to quantitatively separate streamflow into contributions from a current rainstorm versus water already stored within the watershed. In this activity, students collected baseflow and deployed autosamplers before a rain storm, and collect precipitation and streamflow samples during the storm. After analysis of the samples on a laser spectrometer, students used their data to complete a hydrograph separation and interpret results. Full descriptions of the activities, supplies needed, and data are freely available online in peer-reviewed literature or websites.

Each activity was taught at least three times to multiple groups of undergraduate geology majors in different courses, with varying levels of hands-on engagement by students in the field and laboratory. Before and after each activity, content knowledge was assessed with exam-style questions and surveys designed to identify the influence that the environment has on students’ approaches to learning were conducted. Focus groups were also conducted after the course was completed.

All instructional styles appeared to be equally effective at increasing student content knowledge of stable isotopes in the geosciences, although a richer understanding of student gains could be achieved by moving beyond exam-style assessments of learning. Students reported that hands-on experiences were not new to them, because this is the way that many upper-level geoscience classes are taught (e.g., labs, field trips), so the hands-on learning approach examined here may not have the impact it could have with students earlier in their undergraduate careers, in other fields, or at institutions where hands-on approaches are not the norm. 

Examination of survey data on student learning approaches, perception, and motivations may also help explain the findings. Perception of choice, regarding pace and direction of the class, was significantly higher in the “lecture only” case than in the teaching modes with more active learning. Students who used surface learning techniques exhibited lower self-efficacy, critical thinking, and metacognitive approaches, and they had more negative perceptions of course logistics. These results suggest that the success of hands-on activities in terms of influencing student perceptions and motivations may be affected by the students’ approach to learning, and that one activity is not enough to shift such approaches. The “messiness” of hands-on activities and authentic research experiences may be perceived as negatives by students, particularly those who use surface learning techniques and extrinsic motivation.

Last Modified: 11/29/2017
Modified by: Anne J Jefferson