Years ago, I taught English as a Second Language at a pair of schools in Southern California that drew learners from around the world. The students were an absolute joy, enthusiastic about being in America and eager to learn all about our ways (and, especially if they were young men, maybe pick up a cool curse word or two they might not already be familiar with). As one of the first Americans they got to know, I always felt a responsibility to be a good ambassador, aware that some of them would only be here for a short time and then go home to share their experiences with family and friends. So I tried to be available to answer questions before or after class on a range of subjects, both...