Do Digital and 3-D Printed Specimens Increase Conceptualization of Soil Structure?.

Many introductory students studying soils have difficulty conceptualizing the three-dimensional (3-D) character of soil structure. Because the processes that create or are modified by soil structures are often linked to their form, an inability to conceptualize soil structure in 3-D would likely act as a barrier for understanding soil processes such as clay illuviation, natric horizon development, or the formation of slickensides. The goal of this work was to address the problem of conceptualizing soil structure by creating a digital library of 3-D scanned soil structures using a laser scanner and fabricating physical plastic models of these specimens using a 3-D printer. Multiple specimens representing granular, platy, angular and subangular blocky, wedge, and prismatic structures were digitized and subsequently fabricated in plastic. We developed software to allow students to easily interact with the digital soil structure specimens. In order to investigate best-teaching practices using these two materials (i.e., digital and plastic), two types of laboratory exercises were developed that followed either (1) a traditional passive learning approach or (2) an active learning approach. In the passive approach, students were given a short lecture explaining the concepts needed to understand the laboratory assignment prior to each exercise. In the active approach, students were given the exercises to complete with only a minimal amount of soil background information; teaching assistants (TAs) discussed the answers with the students and followed up with a short lecture explaining the concepts after each exercise. The two materials and approaches were combined (a total 4 treatments) and stratified by TA in a randomized block design factorial experiment in an introductory physical geography course at the University of Kansas during Spring of 2014. The effectiveness of digital and 3-D printed models in enhancing conceptualization of genesis, properties, and function of soil structure will be presented and discussed.