Evaluating the Educational Value of Molecular Structure Representations

Abstract

An investigation examined the value of various representations (e.g. concrete three- dimensional models, virtual computer models, static two-dimensional computer models, stereo-chemical formulas) in supporting the achievement by students of an effective perception of molecular structures. Additionally, the usefulness was studied of concrete three-dimensional models, virtual computer molecular models, and their combination, as help tools for students in solving spatial chemistry tasks involving three-dimensional perception, rotation and reflection. Altogether 477 students from secondary schools (age: 18-19 years) took part in the investigation. For purpose of the inquiry a set of four Molecular Visualization Tests was developed. Information about students` manner of thinking while solving spatial tasks was initially gained with a questionnaire and then examined in depth with a structured interview. The data was processed by methods suitable for the respective quantitative and qualitative approaches taken. The results suggest that the information sources which serve as a foundation for students` perception of molecular structure decrease in value from concrete models, to virtual models, to static computer models. Students` perception of three-dimensional structure was better when a stereo- chemical formula was used in comparison to that supported by a computer image. The results indicate that both molecular models types used as help-tools can ease the solving of chemistry tasks that require three-dimensional thinking. Virtual computer models seem to be as effective as concrete models, but the combined usage of both can cause splits in students' attention and therefore seems to be less appropriate.