A history teacher who was videotaped telling his students that only dumb people join the U.S. military has been fired by the suburban Southern California school district where he has taught for more than 15 years. El Rancho Unified School District President Aurora R. Villon announced Gregory Salcido’s dismissal at Tuesday night’s school board meeting. She said he would remain on unpaid administrative leave pending any appeal he might make to state officials. In January Salcido upbraided a 17-year-old student for wearing a Marines sweatshirt to his class at El Rancho High School, telling him members of the U.S. military are “the lowest of our low.”