Students in Harvard University’s introductory computer science course are getting their first test when they opt for one of 3 courses.

The young scholars will be able to choose from among a certificate, a $350 voucher, or academic credit upon completing the class. Inside Higher Ed’s Carl Straumsheim has the details on the business model experiment.

Harvard University will this spring offer three versions of its Introduction to Computer Science course, each with its own level of rigor and student-instructor interactivity. With a paid option that offers students a discount toward future studies at the university, the course represents yet another attempt to find a sustainable business model for massive open online courses.

The course can be taken for no academic credit as a free, self-paced MOOC through HarvardX, the university’s branch of edX, and also as a credit-granting online course through the Harvard Extension School for $2,050. The school is also offering a third path that blends the flexibility of the HarvardX course with biweekly, online office hours with senior lecturer David J. Malan and a discussion forum moderated by teaching fellows. That hybrid option, which costs $350, can be completed for an official certificate, and the cost is returned in form of a discount on a future course through the Extension School or Summer School.

A spokeswoman for the Extension School declined to speak on the record about the course, stressing that the experiment is one faculty member’s idea to rethink his course. Yet a spokesman for HarvardX described the course as a “pretty ambitious revenue experiment” that shows “the ways that MOOCs continue to expand [and] surprise us.”

The Extension School provided preliminary data about the popularity of each version, which suggest the $350 option is not cutting into demand for the credit-granting course. The free version of the course, CS50x, has, not surprisingly, attracted the most students — more than 174,000, according to Malan. About 100 students have signed up for the traditional online course, CSCI E-50, and another 100 for the hybrid certificate granting option. Students have until Feb. 3 and April 4, respectively, to register for the paid versions of the course.

Apart from a reference to it on the HarvardX page, the $350 certificate option has yet to be advertised. A spokeswoman said the university will do some “light marketing” in the weeks before registration closes.

Despite the apparently popularity of the hybrid option, chatter on social media suggests some students are unsure of the worth of a certificate from the Extension School. Several members of course’s official community on the social network Reddit, for example, said they were torn between completing the course for a free edX honor code certificate and paying the $350.

“I have been very tempted to shell out the $350 and get a more worthy certificate, however, I’m wondering how beneficial the certificate would be in the real world,” one user wrote.