Modern shoppers needs are so well known thanks to sophisticated technology, that your supermarket can now anticipate the effect local weather conditions will have on sales. It all began in the US in 1916 with Piggly Wiggly stores (customers wiggled their way round the maze of aisles). At the height of the Depression, the Big Bear chain provided discount food and entertainment - performing bears dressed like customers. Retail theatre is back, but thankfully these days it's just chefs (page 8). TESTeacher will return on April 23.