Abstract

Classroom instruction on geologic structures often involves models demonstrated by the instructor, and/or student construction of paper or clay models. While these models can be useful for conceptual learning, they each have significant downsides. Student-constructed models require significant class time to make, and students' subsequent learning can be hampered if their models do not illustrate key features well. Use of only instructor demonstrations of more permanent or expertly constructed models is less desirable than hands-on manipulation by students themselves, but a full classroom set students can explore is often prohibitive because of constraints on space, money, time, or construction challenges.

I developed a set of activities for introductory geology courses using a guided exploration of easy-to-construct craft foam models of fault blocks and loose sheets that allow students to create common types of faults and folds by application of directional stresses. Since using the models and activities in physical geology, student discussions using the foam models instead of constructing their own clay models have focused more on conceptual understanding, and scores on assessment questions targeting links between stress types and related geologic structures have improved. Common student learning difficulties are less common after instruction and practice, and student satisfaction increased.

Context

I use the activities and foam models as part of a lab session for an introductory college-level physical geology course that serves both majors and non-majors at a 2YC, but they could be adapted for other settings as well as implemented as a shorter activity. Students work on the activities after practice with common stress and geologic structure terminology and concepts in an interactive lecture setting. The main purpose of the activities as I implement them is for students to explore the relationship between stress types, deformation styles, and the geologic structures each produce. Through a hands-on guided exploration, students work in teams to manipulate the models, sketch structures produced, and measure the total length of the fault blocks. They articulate their understanding by answering questions as they go and by summarizing connections in a table at the end of the exercise.

Why It Works

The craft foam fault block models are relatively inexpensive, long-lasting, and a class set can be quickly constructed with layers of readily available craft foam sheets and cut with a table saw. Because the models are standardized and a set is available for each student team to manipulate, students can follow a guided exploration of applying different stresses and sketching structures as well as measuring the total length of the blocks, or can pursue more inquiry-based activities. Stacked layers of loose foam sheets can also be manipulated to make folds. The foam model sets are small enough to be easily stored, and can be loaned to students desiring more practice or who are making up activities.

Typical activities using geologic structure models do not seem to cultivate more expert-like thinking among students in their ability to connect directional stress with geologic structures created by these stresses, nor do they target common student learning difficulties with concepts or spatial thinking. For example, students commonly connect anticlines with compressional stress, but even after instruction and practice, many match up synclines and tensional stress, presumably because faults having a one-to-one match with different directional stress types.

Activities made available for this demonstration are specifically designed to scaffold students through common difficulties, and guide them towards developing more expert-like thinking in connecting structures with the conditions that form them, and hence in using structures to interpret past processes on Earth. The craft foam models assist in student learning as they are available for hands-on use, do not require extensive student construction, are standardized and accurately show key features. They are relatively easy and inexpensive to construct, and require minimal storage space, all features attractive to instructors.