Abstract
This article focuses on whether pupils and students can distinguish between axially and non-axially symmetric shapes and whether they can successfully determine the number of axes of symmetry of a particular shape. In order to research this matter, 1,458 Czech pupils and students of various ages took written tests.
The data was analysed accordingly, and further analysed to determine whether the success rate in these tests was higher among older pupils and students. The results showed that the Czech pupils had no difficulty in finishing the standard tasks successfully.
A considerably lower success rate in the determination of the number of the axes of symmetry of non-standard shapes can indicate an insufficient understanding of the concept of axial symmetry. In order to determine a possible cause for the occurrence of frequent mistakes, contemporary mathematics textbooks were analysed.
Finally, some recommendations for preservice mathematics teachers are presented.