For millions of students worldwide, free, open courseware provides a window, if not a front-row seat, to top university classes. The formats are as varied as the people who tune in. Some consist mainly of lectures recorded on iTunes, while other courses seek to replicate a classroom experience by offering study groups, computer-graded tests, and weekly assignments. And while you might get a badge or certificate showing you mastered the material, you generally won't get direct interaction with the professor, who may have recorded the lectures a few years ago. Here is a look at five introductory economics classes: four through open courseware and one in a traditional classroom.
  Videotaped lectures: Contact with professor: Interaction with other students: Option to take quizzes, tests: Reading/homework assignments
U. of California at Berkeley
Course: "Introduction to Economics"
Format: 23 audio lectures on iTunes
Overview: The university's online video and audio service, webcast.berkeley, offers free audio lectures on iTunes for a variety of classes. Students who take a free online course can supplement their studies by logging on to the same class Web site that posts content for regular, paying Berkeley students.
Chronicle of Higher Education Chronicle of Higher Education Chronicle of Higher Education Chronicle of Higher Education Chronicle of Higher EducationStudents can log on to the class Web site at Berkeley and see slides, problem sets, sample exams, and chat-room notes.
Massachusetts Institute of Technology
Course: "Principles of Microeconomics," OCW Scholar version 
Format: Videotaped lectures and problem-solving videos with exams
Overview: MIT, the world's leader in providing free online course materials, recently unveiled its OCW Scholar program, a souped-up version of its open courses that supplements lectures with optional study groups, videos, simulations, and tests.
Chronicle of Higher EducationLecture videos and problem-solving videos Chronicle of Higher Education Chronicle of Higher EducationOption to join study group through OpenStudy, an online peer-support group Chronicle of Higher EducationMidterm and final exams, several multiple-choice quizzes Chronicle of Higher EducationSuggested textbooks and supplemental study material; problem sets with solutions
Peer 2 Peer University (P2PU)
Course: "Microeconomics: An Introduction"
Format: Volunteer teachers guide students working in groups through open courseware; badges awarded upon completion
Overview: P2PU adds the element of study groups, with volunteer organizers leading students as they work on open courseware from leading universities and other open-education material found on the Internet. Volunteers, who are expected to have some background in the subjects, submit ideas for courses, create syllabi of open courseware, and organize group study.
Chronicle of Higher EducationOptional guest lectures Chronicle of Higher Education Chronicle of Higher EducationAsynchronous discussions with other students Chronicle of Higher EducationQuizzes and final exam Chronicle of Higher EducationOpen-source material provided by the Saylor Foundation; readings and exercises
Saylor.org
Course: "Principles of Microeconomics"
Format: Content gathered from leading universities, awards certificate upon completion Overview: Saylor.org, a nonprofit group that hires professors to collect and post free online content from leading universities, offers more than 200 self-paced courses.
Chronicle of Higher EducationOptional guest lectures Chronicle of Higher Education Chronicle of Higher Education Chronicle of Higher EducationAutomatically graded quizzes, final exam Chronicle of Higher EducationFree lecture notes, links to online reading
U. of Wisconsin at Madison
Course: "Principles of Microeconomics"
Format: Traditional classroom-based course, for which enrolled students pay normal university tuition and earn credits toward a degree
Overview: This introductory economics course at the University of Wisconsin is taught in a traditional format for tuition-paying students.
Chronicle of Higher Education Chronicle of Higher Education Twice-weekly lectures, regular office hours, and by e-mail Chronicle of Higher Education Required weekly discussion sessions with teaching assistants; students permitted to work together on weekly problem sets Chronicle of Higher Education Two midterm exams and one final Chronicle of Higher Education Required text is Microeconomics by Paul Krugman and Robin Wells; weekly problem sets
—Compiled by Katherine Mangan