The boom in online education has created a job that didn’t exist a few years ago: remote test proctor.

More than 100 of them work for ProctorU, a fast-growing startup founded in 2009. Sitting at computers in ProctorU’s offices in Hoover, Alabama, or Livermore, California, the proctors use webcams and screen-sharing software to observe students anywhere as they take a test or complete an online assignment. As the students do the work on their computers, the proctors watch to make sure they don’t cheat.

It’s a simple idea that could prove critical for the expansion of online education. Over the last year, several top universities, including Harvard, Stanford, and MIT, have begun offering free college courses to all comers (see “The Crisis in Higher Education”). After attracting hundreds of thousands of students, these “massive open online courses,” or MOOCs, are now wrestling with how to determine which students are actually completing the coursework and passing exams.

That will be vital because the chance to offer students “certified” results—and a course certificate—will probably be the key to ensuring that MOOCs are financially sustainable. EdX, the digital education partnership between MIT and Harvard, thinks it can charge students $100 or so if they want to obtain an official completion certificate. Other MOOCs, such as the for-profit Udacity and Coursera, hope to make money by connecting their best students with recruiters and employers.

With this in mind, edX, Coursera, and Udacity are working with the education publisher Pearson to allow students of online courses to take exams at a testing center run by Pearson. These centers can be found in more than 100 countries. But even a network that widespread won’t reach every prospective student.

More than 200 colleges and technical schools have hired ProctorU to administer tests that students can take at the same computers where they took their MOOCs—though ProctorU also oversees tests for traditional classes. “Almost every class now has an online component to it,” says Don Kassner, ProctorU’s CEO. “And some of these schools are realizing the logistics of scheduling 350 students into a class for a final exam is difficult.”

Many of the proctors hired by ProctorU are college students themselves. They get 75 cents per hour above minimum wage (which means they make $8.75 an hour in California and $8 an hour in Alabama) and get a raise of $1 per hour after a 90-day evaluation period.  A proctor must watch and answer questions from as many as five or six test-takers at one time, so Kassner says he tries to hire people who are proven multitaskers, like avid videogame players or people who have worked in restaurants.

Proctoring tests offers a remarkable window on the world, says Franklin Hayes, who has administered exams for the company since 2011 and doubles as its media-relations officer. In addition to watching college students in their dorms and apartments, he’s given tests to soldiers in Afghanistan and to people who hope to pass highway-paving certification courses. Once a police officer logged on to take a professional certification test from the laptop in his squad car.

Proctors must also steel themselves to be mooned or worse; some test-takers can’t resist exposing themselves to the proctor on the other end of the videoconference. “One of the things we train our proctors on is, `You’re going to see some things you didn’t want to,’ ” Kassner says.

Perhaps because the proctor-to-student ratio is higher than it might even be in a traditional college classroom, cheating appears to be relatively uncommon. The proctors file an “incident report” to a student’s school if they spot something inappropriate; that might include a suspiciously severed Web connection, someone coming into the student’s room, or the student sneaking a peek at a textbook. Kassner says incident reports get filed for only seven out of every 1,000 exams.

Sometimes a proctor’s job is to remind students they can’t consult Google. Test-takers see the proctor at the beginning of their exams, but are free to minimize the videoconference window on their screens so they don’t have to feel stared at. With the proctor invisible, it’s not uncommon for students to forget and open a new tab in their Web browser.

The proctors can see that happen through the screen-sharing software that test-takers have to run on their computers. “We can intervene and say `Please close that tab,’ ” Hayes says. “Most of the time, people are nice about it and close the tab.”