A drill sergeant passes a row of recruits -- many of them high school juniors and seniors -- headed into their first day of military life at the Army National Guard complex in Marseilles, Ill. Jeff Roberson/AP hide caption

itoggle caption Jeff Roberson/AP

Sarah Reeves, 19, dances the schottische with Ryder Cude, 15. Vikiann Gunter for NPR hide caption

itoggle caption Vikiann Gunter for NPR

More American colleges are offering classes that teach students to deal with a shrinking and increasingly dangerous world. iStockphoto.com hide caption

itoggle caption iStockphoto.com