DEVELOPING PROBLEM-BASED LABORATORY EXERCISES IN IGNEOUS PETROLOGY: NO PLACE LIKE HOME

Undergraduate students enrolled in petrology courses are faced with a daunting task of learning how to collect basic petrographic information along with memorizing a substantial number of new terms and definitions prior to being able to comprehend petrogenetic processes. Teaching these fundamental skills can occupy a significant amount of laboratory time, leaving little opportunity for students to synthesize their observations or to connect their newfound insights to lecture concepts. We have developed new laboratory exercises for our igneous petrology class that introduce the students to igneous processes from the very first lab. In order to provide the students with a framework for learning new material, we base the laboratory exercises on igneous rocks from tectonic localities in California, but at institutions where local rock suites aren't easily accessible, classic localities could be equally effective. Each lab targets central petrologic concepts that the students need to know in order to relate their petrogenesis to their tectonic setting. The format of the labs are 1) an introduction to the geologic/tectonic background of the region including photographs, figures, and geologic maps illustrating where the samples were collected as well as any new terminology, 2) questions to aid in collection of petrographic data, and 3) a synthesis portion that draws upon these data and consists of interpretative questions, ultimately allowing their to investigation of more complex igneous problems. With seven new exercises, we were able to present the major petrologic processes and tectonics environments thereby complementing the concepts covered in lecture.

An assessment of student learning in this new class format was accomplished by gathering the student's feedback in the form of post-class questionnaires and also evaluating their efforts on a final project that has been the same for the past nine years and involves collecting petrographic data from suite of unknown rocks and development of a liquid line of descent. Scores for the students who took the revised version of this class were consistently higher than those from the last twelve years.