Testing and improving students' understanding of three-dimensional representations in chemistry.

[摘要] Three-dimensional visualisation is an important skill inchemistry but one in which many students experience difficulty.The main aims of this research were to identify the nature,extent and particularly the reasons for university students'difficulties in three-dimensional thinking and to devise teachingstrategies for overcoming them. The research was restricted tothe simpler aspects of three-dimensional thinking; it dealt onlywith rotation and reflection of simple molecules.The component steps required for the solution ofthree-dimensional problems were identified, and students'competence in these steps was tested. Pretest results showed thatthe students initially had poor visuaIisation skills. The mainreasons for their difficulties were identified to be: (a)inability to visualise the three-dimensional structures ofmolecules, using the depth cues; (b) lack of preciseunderstanding of the meaning of the phrases used in the questions(such as rotation about the X-axis; reflection in the XY plane);(c) inability to visualise the orientation of the axes and planesand of the positions of the atoms after an operation.A ninety minute remedial instruction programme on those aspectswhich caused difficulty was found to be enough, as shown by ananalysis of covariance, to improve the students' visualisationskills very significantly (p < 0,01).

[发布机构] University of the Witwatersrand