Abstract
The experiment concerns a teaching method based on the use of overhead‐projection transparencies containing a sequence of diagrams to represent a three‐dimensional structure at different stages during a rotation. When the diagrams were exposed one at a time, or were monochrome, there was no significant learning by a sample of Bahraini students. However, when the transparencies contained multi‐coloured diagrams which were exposed simultaneously or individually in a cumulative manner, there was significant learning.