USE OF DIGITAL AND 3-D PRINTED SOIL STRUCTURE SPECIMENS IN AN INTRODUCTORY GEOSCIENCE LABORATORY

Many undergraduate students enrolled in geoscience courses have difficulty visualizing important three-dimensional (3-D) components of the terrestrial environment such as soil structure. This is unfortunate because the processes that create these 3-D structures are often linked to their unique, irregular forms. Hence, problems visualizing 3-D structures will lead to problems understanding Earth surface and subsurface processes. In this work we attempted to address the problem of conceptualizing soil structure by creating a digital library of 3-D scanned soil structures using a structured-light technique known as multistripe laser triangulation (MLT) and fabricating physical plastic models of these digital specimens using a 3-D printer. Multiple specimens of granular, platy, angular and subangular blocky, wedge, and prismatic structures were digitized and fabricated in ABS-plus plastic. We also developed Java-based software to allow students to easily access and interact with the digital specimen files. In order to investigate best-teaching practices using these two materials (i.e., digital and plastic), two types of laboratory exercises were developed. In the first type (a traditional passive learning approach), students were given a short lecture explaining the concepts needed to understand the laboratory assignment prior to each exercise. In the second type, students were given the exercises to complete with only a minimal amount of soil background information (an active learning approach). Graduate teaching assistants (GTAs) discussed the answers with the students and followed up with a short lecture explaining the concepts after each exercise in this approach. The developed exercises were deployed in place of the usual soil laboratory in 24 two-hour sections of an introductory physical geography course at the University of Kansas during the spring semester of 2014. The two materials and approaches were combined (a total 4 treatments) and stratified by GTA in a randomized block design factorial experiment. The effectiveness of digital and 3-D printed models in enhancing undergraduate understanding of the genesis, properties, and function of soil structure for both passive and active learning approaches, as well as the potential of this approach in other geoscience courses will be discussed.