More than 100 Northwestern University students watched as a naked 25-year-old woman was penetrated by a sex toy wielded by her fiancee during an after-class session of the school’s popular “Human Sexuality” class. The woman said she showed up at the Feb. 21 lecture in the Ryan Family Auditorium in Evanston expecting just to answer questions, but was game to demonstrate. The course’s professor on Wednesday acknowledged some initial hesitation, but said student feedback was “uniformly positive.” And Northwestern defended the class and its professor. “Northwestern University faculty members engage in teaching and research on a wide variety of topics,...