Geology in the lab: preliminar studies for validating a checklist for analysing modelling activities in textbooks

Abstract

Models and modelling activities play a central role in the making and understanding of science [1], making the learning of science more meaningful and helping students to build appropriate mental models [2, 3]. When students learn with models, they build mental ones that are more consistent with scientific models. This reconstruction process is generally complex and generates many cognitive conflicts. It was only in the early 19th century, when J. Hall (1761-1832) resorted to models to corroborate plutonism, that geology, an eminent field science, became a laboratory science. Throughout the years, these models became dimensioned with rules of proportionality, thus acquiring the status of representations of natural phenomena. In the last 30 years experimental modelling has been a subject of fruitful research, mainly using the classic tectonic sandbox models to control parameters for the structural evolution of mountain belts [4]. However, models were integrated in geoscience textbooks for educational purposes and, veiled behind them, many mandatory analogue properties, which are required for research purposes, where forgotten. In fact, many of those modelling activities didn't resort to analogue materials with similar geologic properties, nor did they respect the dynamics, kinematics and geometric similarities. Indeed, respecting the similarity rules is a difficult, time-consuming and an expensive process that may not be justified in some educational purposes. However it is necessary that teachers and textbooks have correct information regarding modelling activities and the kind of analogy they provide. The reduction of time and of space that underlays those geoscience lab activities, as well as the heuristic rule of the models used in geoscience classrooms, needs to be well explained to students. Thus, it is worthwhile to analyze the modelling activities in geoscience textbooks, in order to evaluate their nature and whether or not the syllabus purposes can be accomplished. To do so, an instrument designed to analyze model activities of geoscience textbooks was developed guarantying a reliable, comprehensive and systematic study. Bearing in mind some items and issues that arose from other instruments designed to analyze lab activities, and after reviewing the literature, a first version of the checklist was developed. It encompassed three main dimensions: type of lab activity; type of manipulation of variables; type of models. All three dimensions included a few sub-dimensions further specified. As in other studies [5], the sub-dimensions emerged from the literature as well as from our knowledge on how lab-modelling activities are dealt with in science textbooks. Four researchers carefully undertook the process of analyzing the 35 lab activities from three geoscience textbooks, in two rounds. The results of the first round were presented to all researchers in order to promote reflection and an improvement of the checklist. A consensus was established after the second round, which was applied one month after the end of the first analysis. Although developed by resorting to Portuguese textbooks, the checklist may be used as a referential for a more comprehensive and meaningful analysis of textbooks from other countries, a task that can be regarded as a follow up study, further increasing its validity.