Pluralism includes mainstream economics. Our campaign for pluralism, including this series, have generally focused on ideas outside the mainstream on the basis that it gets plenty of attention already so we want to spend our time exposing people to alternatives. Nevertheless, mainstream ideas deserve some attention. On top of this, a curious feature of modern economics education is that some of the best ideas from mainstream economics are not even taught to undergraduates! During this series I will explore such ideas, starting today with the market construction technique known as ‘matching’.