P369: Investigating students’ understanding of ionic solids in chemistry with the use of 2D and 3D representations
Visual modeling is an essential tool for teaching science because many concepts involve the understanding of particles that cannot always be observed with the naked eye or even with the assistance of current technology. Chemistry relies heavily on the use of two-dimensional (2D) models to represent the inherently three-dimensional (3D) molecules. Effective models increase students’ representational competence, which is the ability to communicate, think, and practice learned knowledge experimentally. Representational competence encompasses the connection between the visual model and the abstract concept represented. One aspect of representational competence is determining whether there is a difference between students’ comprehension when using 2D compared to 3D representations. The purpose of this study is to assess the effect of using 2D versus 3D representations to visually model ionic compounds during physical and chemical changes at the particulate level. The subjects of this study were students who were enrolled in a General Chemistry I course during the Fall 2012, Spring 2013, and Spring 2014 semesters in Southern California. Students’ answers from a pre-lab and a post-lab activity that deals with the physical and chemical change of ionic solids with the use of visual representations were evaluated. Data analysis includes a comparison of mean scores by independent samples t-tests. Preliminary results show that students score higher on assessments with 2D than 3D representations of ionic solids. This study may serve as a precursor to the development of an assessment of representational competence.