SUMMARY. The aim of this investigation was to determine the structure of abilities underlying the visualisation of rotations about the three Cartesian axes for three-dimensional structures presented as models, on the one hand, and diagrams, on the other. The investigation was carried out by administering a test as two versions which required students to visualise the same rotations of the same structures presented as models and diagrams respectively. There were no factors common to the rotations with models and diagrams. The resulting factor pattern for models had two factors, one characterising rotations about both the X-and Y-axes, and one characterising rotations about the Z-axis. The pattern for diagrams had three factors, one for rotations about each Cartesian axis. Theoretical and educational implications are discussed.
INTRODUCTIONAT all educational levels, diagrams and models are used as teaching aids to represent three-dimensional objects or structures. Moreover, the diagrams are drawn, and the