Last month we wrote about a professor’s experiment in “open teaching,” in which he allowed anyone to take his online course and fully participate in discussions. Since then readers have alerted us to at least three other experiments in open teaching, in what appears to be a growing movement.

More than 2,000 people have signed up to be informal students in an online course on “Connectivism and Connective Knowledge” taught by Stephen Downes, a senior researcher at the National Research Council of Canada, and George Siemens, associate director of research and development at University of Manitoba’s Learning Technologies Centre. Students can add to a course blog and a wiki, and read highlights on a daily e-mail newsletter. At least one day a week, everyone can tune in and ask questions during a multimedia Webcast. Think radio call-in show with professors as hosts, says Mr. Downes. Twenty-four students have enrolled to take the course for credit through the University of Manitoba.

In January some 200 students informally followed a course by Alec Couros, information and communication technology coordinator for the School of Education at the University of Regina, in Saskatchewan, called “Open, Connected, Social.” Mr. Couros said his motivation was to practice using various social-networking tools and to see if it was possible to use Web 2.0 to make it easier to teach more students online than would otherwise be feasible. “I’m trying to get an idea of what it would take to be a network teacher,” he said.

And a handful of informal students joined an open-education course taught last fall by David Wiley, then a professor at Utah State University and now at Brigham Young University. He admitted that managing the additional students, and grading their papers, was “a healthy amount of extra work — probably double what I would have spent marking anyway.” But he felt like professors should consider the work part of the service component of their jobs.

What are the implications of open teaching for colleges? I provide my take in the first installment of a new Chronicle column called College 2.0. The mission of the column is “exploring how new technologies are changing colleges,” and I’d love to hear ideas for topics to tackle in future installments. —Jeffrey R. Young