Educators and economists tell us all the reasons college enrollment has been dropping, especially for men, and how to stop the bleeding. (Part 4 of “Freakonomics Radio Goes Back to School.”)

Enrollment is down for the first time in memory, and critics complain college is too expensive, too elitist, and too politicized. The economist Chris Paxson — who happens to be the president of Brown University — does not agree. (Part 3 of “Freakonomics Radio Goes Back to School.”)