First, Mark Bittman, a food writer for the New York Times, plugged the course on Twitter. Author Michael Pollan was next. Then a retweet from Bill Gates, who has 10.5 million followers.

Thanks in part to the tweets from these famous folks, registrations have been flooding the University of Minnesota's upcoming massive open online course Sustainability of Food Systems: A Global Life Cycle Perspective. As of Wednesday, more than 6,100 people had signed on.

As if MOOCs, as they're known, needed any more hype.

Jason Hill, the course's instructor, has watched in awe as the numbers have grown. "It both excites and scares me a little bit," said Hill, a McKnight Land-Grant Professor.

So far, his is the most popular MOOC of the U's first batch of five, which start in May.

Christopher Cramer, a chemistry professor who is also teaching a MOOC, admitted to being "extremely jealous of Jason's high-profile boosters," he joked by e-mail. He figures he will "promote more videos blowing stuff up to try to counter."

The description of Cramer's offering — Statistical Molecular Thermodynamics — suggests that enrollees ought to have taken college-level physics, chemistry and calculus. Registrants: 2,800.

Hill tailored his course to be "very accessible." A growing number of people care about food and sustainability, and Hill has seen interest from those who describe themselves as gardeners and foodies.

Despite the huge class size, he and his teaching assistants plan to read and respond to comments and questions. "It's really meant to be, as much as possible, an interactive process," he said.

In short videos, experts will help Hill answer the course's big questions, such as, "How much food will we need in the future?" He hopes he's created something that, from week to week, keeps students coming back.

All 6,000-plus of them.

"I try to keep in mind that these are individuals," Hill said. "I'm just going to try to teach to one person.

"That prevents me from waking up in the night shaking."

Jenna Ross • 612-673-7168