Sigmatropic rearrangement is one of the main classes of pericyclic reactions, which does not necessarily mean that these rearrangements have a pericyclic mechanism. The allylic saccharin derivative O-cinnamylsaccharin can isomerize into N-cinnamylsaccharin in the polar solvent system toluene/triethylamine in a reaction time of 2 h at 110°C. The mechanism of this reaction is pseudopericyclic and may be elucidated using theoretical calculations. However, this is not an easy topic, and therefore, it should be taught in phases and using the three main resources: theoretical classes, laboratory experiments and computer experiments. Here I aim to explain this perspective. [For "Pericyclic or Pseudopericyclic? The Case of an Allylic Transposition in The Synthesis of a Saccharin Derivative," see EJ1159631.]