At most colleges and universities in the U.S., students take a yearlong introductory sequence that covers both Micro and Macro. At Columbia, we only have a one semester Principles course which does not cover as much material and in particular, does not present some of the most basic models used in the upper level electives. The two intermediate courses (Micro and Macro) cover all of the basic theoretical topics and major issues in economics and provides students with an overview of the analytical techniques utilized in the discipline. Thus, at Columbia, we require that you complete your intermediate courses before you begin studying the individual fields of economics, so you are equipped with the necessary technical skills and perspective to understand the upper-level electives.