“I was a little scared to put our kids, who are struggling and at risk of dropping out, into a class written by a Stanford professor,” said Melody Chalkley, Winfree’s founder. “But of the 23 students who used Udacity, one withdrew from the school, and the other 22 all finished successfully. And two young women got through the whole physics course in just two weeks.”

Until now such courses have been seen as a threat to professors’ jobs. The San Jose chapter of the California Faculty Association has not yet taken any formal position on the Udacity pilot. Many members were not aware of it, and some of those who did know of the plan said they had learned of it only informally.

“My personal opinion is that it’s not by accident that this is being announced at a time when most faculty are not on campus, but I have no evidence for that,” said Preston Rudy, a sociology professor at San Jose State who serves as vice president of the chapter. “I don’t know enough about Udacity to take any position, but over all, I know the university is concerned about who will teach courses if they go online, who has control, and whether they will be university employees.”

The Udacity deal could blunt some faculty opposition, because the effort will continue to involve professors — but it will also use online course assistants, or “mentors,” hired and trained by Udacity.

The program is an attempt to overcome the biggest failure of open online courses today — their 90 percent dropout rate.

Despite high enrollments, about half the students who sign up for such courses, whether at Udacity or other providers, fall away at the beginning, never even looking at the first assignment. Many of them are browsers without real commitment to the classes. But others, Mr. Thrun said, just need more support.

“I am personally troubled by the 90 percent dropout rate,” Mr. Thrun said. “The students signing up are highly motivated — and MOOCs will only succeed if they make normally motivated students successful.”