The 10-week course, titled “Constitutional Struggles in the Muslim World,” is taught by Ebrahim Afsah, associate professor of public international law at the University of Copenhagen. His experiences highlight an important challenge that the scale of MOOCs presents: How do you wrangle tens, perhaps hundreds of thousands of students into staying on topic? A traditional face-to-face course might fare well with one or two troublemakers, but those interruptions are magnified when enrollment reaches the thousands -- especially if those students can post anonymously.