Starting pre-school poses tests for any four-year-old: sitting still, the risk of a yucky lunch, missing home, The Economist reports. The stakes are still higher for 700 small Texans due to enter pre-kindergarten centres being opened by the city of San Antonio on August 26th. They are pioneers who will be watched all the way to the White House. Not so long ago there was broad, bipartisan support for government provision of pre-school (called “pre-K”, since it precedes kindergarten): a year of classes and play designed to ensure that children are ready for the serious business of learning. Alas, pre-K has joined the long list of issues capable of provoking partisan rage. Critics include shrink-the-government types growling about expensive “babysitting”, joined by social conservatives arguing that young children are best off when cared for by married mothers, at home…