Design and implementation of interactive online tutorials for introductory soil science courses

摘要

Introductory soils courses contain many physical and chemical concepts on a microscopic level that are often unfamiliar to students. Hence, many undergraduates in agriculture consider it to be one of the more difficult introductory courses. With theadvancement in information technology, difficult concepts can now be modeled and delivered in an interactive format that allows students to develop a more solid understanding of basic soils. Accordingly, the objective of this project was to develop interactive tutorials for clay mineralogy and cation exchange capacity (CEC) that could be delivered over the World Wide Web. For the clay mineralogy tutorial, the students were introduced to the basic building blocks of clay minerals, the tetrahedron, and octahedron. From there, these were polymerized and combined into various layer silicate minerals. For each of the minerals a Quick-Time virtual reality (VR) movie allowed the student to rotate the structure with a mouse. For the CEC tutorial we used a Crystalmaker model of a montmorillonite particle. Exchangeable cations scaled to their hydrated radii were placed in the interlayers of the montmorillonite particle to satisfy the charge developed via isomorphic substitution. Both the exchangeable cations and clay particles oscillated in the model to simulate Brownian motion. Cations in solution were programmed to move and exchange with cations on the surface of the clay particle, thereby demonstrating stoichiometry of the exchange reaction and the conceptof CEC. These tutorials allow the student to move through a concept at their own pace and are ideally suited for distance education.