When political science professor Ian Shapiro recorded an online class for Open Yale Courses five years ago, he simply had his regular lectures in the Whitney Humanities Center auditorium filmed. But this winter, in creating his first massive open online course, or MOOC, Shapiro was able to experiment with several options in an advanced film studio before settling on a new, experimental method: a Socratic-style dialogue between Shapiro and two hired “students,” who respond to his questions during the filmed lectures.

Three of Yale’s five spring 2015 MOOCs — Shapiro’s “Moral Foundations of Politics,” music professor Craig Wright’s “Introduction to Classical Music” and Yale Law School professor Akhil Amar ’80 LAW ’84’s “America’s Unwritten Constitution” — begin today, marking a continued expansion of the University’s online course offerings. Art history professor Diana Kleiner’s “Roman Architecture” MOOC is slated to begin this February, and School of Management Professor Barry Nalebuff’s “Introduction to Negotiation” will likely start in March.

While “Roman Architecture” and a version of “America’s Unwritten Constitution” have been offered before, the other three MOOCs are new this semester.

“One trend that we are really excited about is that when we run a course a second time, we see a much more engaged audience registering for the course,” Executive Director of the Office of Digital Dissemination and Online Education Lucas Swineford said.

Audiences for Yale’s courses continue to grow, Wright said.

The percentage of students who elected the Signature Track — a paid version of a course that provides students with certification — for economics professor Robert Shiller’s “Financial Markets” course nearly doubled the second time the MOOC was offered, Swineford said.

Professors said they enjoy teaching MOOCs because the online courses provide an opportunity to share course material with interested students all over the world. Students can opt to take the courses, which are offered on the online platform Coursera, for free, or via the Signature Track.

“[MOOCs are] a 21st-century version of a public library,” Amar said.

However, adapting a traditionally taught lecture or seminar into a MOOC requires adjustments in both teaching and class assignments, professors said. Nalebuff has hired several Yale School of Drama students to act out negotiation scenarios in the videos. He said teaching this MOOC will also change the way he teaches the live version of the course, as much of the material he covers will already be available online. Amar said that he focuses more on images in his MOOC than he would in a traditional classroom setting, as the online version is a far more visual medium.

Wright said the challenge is to create questions that involve deep critical thinking but are clear enough that a computer can grade them. Machine grading is necessary given the tens of thousands of students taking the courses, he said, but it is not yet clear whether computers work as well as professors in assessing student work.

“We don’t know if something is lost,” Wright said. “What we as educators have to put more emphasis on, I think, is evaluating the success of the teaching we do.”

Coursera currently offers 892 courses from 117 partner institutions.

Correction: Jan. 12

A previous version of this article misstated that that the number of students who chose the Signature Track in “Financial Markets” doubled. In fact, the percentage of students electing the track doubled.