In the Wall Street Journal, Peter Berkowitz says you probably didn't. And it shows:
It would be difficult to overstate the significance of The Federalist for understanding the principles of American government and the challenges that liberal democracies confront early in the second decade of the 21st century. Yet despite the lip service they pay to liberal education, our leading universities can't be bothered to require students to study The Federalist—or, worse, they oppose such requirements on moral, political or pedagogical grounds. Small wonder it took so long for progressives to realize that arguments about the constitutionality of ObamaCare are indeed serious.
Explains a lot, really.