An hour-long TV special, now in its second week on District airwaves, begins with images of families in immigrant detention centers, as a voice-over asks, “ Isn’t everyone welcome in America?... And many of the other people behind the special are more students just like him. The town-hall-style program, titled “ Race in America: Teens Speak, ” has been airing on the government-run District Knowledge Network( DKN) since Dec.... 5, with another that was scheduled for Saturday night and additiona