I can imagine now that the last class of the week on a Friday afternoon is not one for which teachers have any particular fondness, despite the promise of freedom that lies after the final bell. For my twelve-year-old self, the weekend was the light at the end of the very long tunnel that was double chemistry with Mr. Walters. The Friday I remember so vividly was in winter; the light was already fading and it would be dark before I got home. It always seemed that the best and brightest part of the day was wasted in school – until Mr. Walters introduced me to the alkali metals.