Recent changes in the teaching of special relativity

A personal view of recent developments in the teaching of special relativity are described in terms of the author's change of approach. The main reasons for this development are summarised as: (1) The concept of the photon is now in the A-level physics syllabus. (2) There are now a large number of experiments on high-energy physics using cosmic rays and accelerators. (3) Radar methods are in common use. (4) There is now direct experimental evidence in favour of the principle of the constancy of the speed of light. (5) The K-calculus, based on space-time diagrams and radar methods, has been introduced. (U.K. )