What if you could reach 50,000 members of a target audience all at once?Law schools using MOOCs do just that.Now University of Chicago Law School is getting into the action.A MOOC, or massive open online course, is a free online course open to the public with unlimited enrollment and online video lectures.This summer, the University of Chicago will host its fifth MOOC since September 2013 and the first for the law school.The course, “Internet Giants: The Law and Economics of Media Platforms,” will cover seven …