As an ex-schoolteacher of 'sums and drums', headmaster O'Connor dons his tattered mortar-board and takes a backwards glance at learning. Aided by his erudite pupils, CHRIS EMMETT and CAROLINE GRUBER , as well as story-tellers JEFF STEVENSON and MICK WALKER (still in their short trousers), Tom tries to find the roots of Pythagoras' theorem of laughter. Guest, Paul Shane , appears from behind the bicycle sheds to visit, and the 'public at large' gives its version of the verb 'to learn'.