Some time ago in 2010, I showed a chemical problem I used to set during university entrance interviews. It was all about pattern recognition and how one can develop a hypothesis based on this. In that instance, it involved recognising that a cyclic molecule which appeared to have the cyclohexatriene benzene-aromatic pattern 1 was in fact a trimer of carbon dioxide. Perhaps small amounts of this aromatic molecule exist in solutions of fizzy drinks? Analysing these patterns occupied about 10-20 minutes of an interview, and although you might think I was posing a difficult challenge, many students successfully rose to it! Now I revisit, but with a slightly better reality check on a related molecule 2 (cyanuric acid).