GSA Annual Meeting in Denver, Colorado, USA - 2016

Paper No. 284-6
Presentation Time: 9:30 AM


HANNULA, Kimberly A., Department of Geoscience, Fort Lewis College, 1000 Rim Drive, Durango, CO 81301,

Penetrative thinking is an important skill in structural geology, and is trainable. However, it would be useful to know the extent to which students’ skills improve during a typical course, without the use of additional exercises. This study provides baseline information about improvements in the Geologic Block Cross-sectioning Test (GBCT) in a two-course sequence (sophomore Field Methods and junior Structural Geology).

The GBCT was given as pre- and post-tests to students in Geologic Methods (n = 40) and Structural Geology (n = 50) in Fall 2014 and Fall 2015. On average, GBCT scores (out of 16 possible points) improve in both courses (95% confidence intervals: 3.1 ± 1.8 points for Geologic Methods and 2.2 ± 1.4 points for Structural Geology). Distribution of correct scores becomes more skewed through the sequence of tests; 7 (18%) Methods and 12 (24%) Structure students showed no improvement between the beginning and the end of the course.

The GBCT includes several categories of distractors that can be used to understand the types of misconceptions faced by students. The most common incorrect choice for both courses was the “parallelogram” response – an exact copy of the perspective drawing shown in the question. A parallelogram response suggests that students are not thinking about the interior of the object. It is possible that students need to understand what is wrong with the parallelogram responses before they can solve the most complicated GBCT problems.

Although parallelogram scores decreased during each course (2.0 ± 1.2 in Geologic Methods; 0.9 ± 0.7 in Structural Geology), the decreases are smaller than the increases in correct scores (p = 0.04 for Geologic Methods; p = 0.002 for Structural Geology). This suggests that students switch to correct answers more often than they switch from parallelogram to other types of responses (such as the structure shown on a parallel face of the block).

There are no clear indications from the pre-tests about which students will be least likely to improve their GBCT scores during the course. In Geologic Methods, students who did not improve started with slightly lower pre-test scores and higher parallelogram scores; however, given the small sample size of students who did not improve, the differences are not statistically significant.