Mr. Downes, who writes a well-known education technology blog called OLDaily, permits students to create private groups if they like. But that isn't the default position. He also argues that closed classes provide a lot of latitude for misbehavior, such as prejudice or acting inappropriately toward women.
"People say, 'Well I'm a lot more comfortable in private,'" he says. "I sometimes think of that as meaning, 'I'm a lot more comfortable being a jerk in private.'"