Udacity itself has been beached on the shores of unrealized optimism. In 2011, after discovering wide interest in online learning when he put his Stanford artificial-intelligence lectures online, Mr. Thrun founded Udacity as one of the first for-profit MOOCs — for “massive open online courses.” The idea that MOOCs would pose an existential threat to the elite universities gained cultural cachet. “Nothing has more potential to lift more people out of poverty,” Thomas L. Friedman, the New York Times columnist, wrote in 2013.

Image Credit... Stuart Goldenberg

Actually, that didn’t happen. Mr. Thrun now says that in its first incarnation as a MOOC that tried to offer students a broad, general-purpose education, Udacity attracted many people to its classes, but just about everyone failed to complete the work. So in 2013, Mr. Thrun began reimagining Udacity not as a replacement to universities, but as a more practical vocational school that offered highly structured lessons to help people find jobs.

In an economy constantly riven by technological change, Mr. Thrun says he believes periodic vocational training will become increasingly important in the job market. “It’s a mistake to think that a single college education can carry you for a lifetime,” he said. “To keep pace with change, your education has to be done throughout your life.”

So far, Udacity’s new model shows a glimmer of success. A year after the program’s start, the company has 10,000 students enrolled in its nanodegree courses, and the number is growing by a third every month. Udacity charges $200 a month for the courses (students can take as little or as much time as they want to finish). When they successfully complete a course, Udacity gives back half the tuition. The company says that a typical student will earn a nanodegree in about five months — in other words, for around $500.

Because students take several months or longer to complete their degrees, it is too soon to tell exactly how many will finish. So far, Udacity estimates the graduation rate to be about 25 percent. Thousands of workers have earned degrees, and hundreds have found new jobs as a result.

Mr. Thrun attributes part of the success to the course material, which was developed in conjunction with companies to teach skills that they look for in employees. For instance, Udacity’s Android course is staffed by instructors from Google, which developed the mobile operating system. Udacity’s model also a puts a premium on one-on-one coaching, mentorship, career counseling and job-interviewing skills, all of which keep students more invested in their work.