At one time, protractors and slide rules were the school supplies that students were expected to bring to class and young ladies were advised to leave their Barbies at home. Now, the dolls themselves have become teacher aids and not just in the lower grades. “A month before I got to Duke, the Young America’s Foundation had issued its annual ‘dirty dozen’ list, which identifies the nation’s 12 most ‘bizarre and troubling instances of leftist activism supplanting traditional scholarship in our nation’s colleges and universities,” Elizabeth J. Chin writes in the Chronicle of Higher Education. “A course that I teach...