Stable Isotope Ecology (Even Falls)

In this student-led discussion-based course, we cover a broad overview of stable isotope biogeochemistry and the ecological applications of this rapidly expanding field. We review isotope basics (e.g., terminology, notation) and discuss ecological patterns in naturally occurring carbon, nitrogen, oxygen, hydrogen, sulfur and strontium isotopes in biological organisms. A mix of undergraduate and graduate students from anthropology, geology, geography, and biology take this course. Not surprisingly, these students come to class with a range of backgrounds and interests. Keeping these in mind, I carefully chose papers to encompass fundamental as well as recent advances in the field. I created a private WordPress website for this course ( All readings, assignments, interactive resources, and PowerPoint presentations from each week’s discussion are posted on this website. Unlike Blackboard, these resources will remain available to the students indefinitely.

Rather than test student knowledge using summative assessments like exams, I decided to formatively assess student proficiency by grading their participation in class and assigning a final project. The students and I rotate leading each week’s discussion. Weekly leaders are tasked with guiding our discussion and ensuring that all students participate. The participation criterion has resulted in some dynamic and truly enjoyable activities. Several weekly leaders have assigned additional or alternative readings. I have been repeatedly struck by how much of the material the students understand, especially considering that the vast majority of them had not been previously exposed to isotopic literature. In addition to thoroughly comprehending the reading material, the students ask insightful and thought-provoking questions, many of which have never previously crossed my mind.

The first time I taught this course (Fall 2012), I asked students to design a hypothetical research project using stable isotopes with an emphasis on creativity. Students wrote their projects up in short papers and presented them to the rest of the group during finals week. I made my expectations for this project very clear by providing the students with grading rubrics for the paper and the presentation. In order to help students avoid procrastinating, I assigned several “road checks” throughout the term (e.g., turning in a title, a project description and an abstract part way through the term). On the days when these mini assignments were due, I asked students to spend several minutes discussing their projects with a peer and then reporting what they were working on and what they found most challenging to the rest of the class. I very much enjoyed this part of the class. The diversity and complexity of the projects students proposed were impressive, and clearly thoroughly researched.

In Fall 2014 I modified the course slightly. I had a larger student body (21 students) and I wanted to make sure that nobody slipped through the cracks during discussions. In order to emphasize the importance of critical thinking, I added a new weekly assignment in which students had to write 5-sentence summaries of each week’s readings. Although summaries added more work for the students and myself, they were clearly beneficial. In addition to assuring that all of the students actually did the reading, these summaries allowed me to confirm that everyone was following the weekly topics.


I also retooled the course to include group research projects. Thanks to our new stable isotope laboratory, I was able to incorporate a laboratory component to the course. Now small groups of students design and carry out their own research projects from deciding on a project topic through sample preparation and analysis, data interpretation, and presentation. This change has definitely benefitted the students: they gain a much better understanding of how much work goes into carrying out even a small project, and learn how to critically look at data. However, it has also resulted in a substantially larger workload for everyone (students and me). This is a tradeoff I am willing to take. I work closely with each group as they design their projects and process samples in my lab. I provide supplies and chemicals and we run all of our samples in our Stable Isotope Facility. I then help each group critically evaluate and interpret their data, and I carefully read through each student’s final paper.

Click HERE to view a syllabus of this course