About one of every five elementary school students in the Clark County (Nev.) district attends classes in a portable classroom.The Las Vegas Sun reports that the classrooms were designed to be temporary structures. But as enrollment continues to climb in the nation’s fifth-largest school district, portable classrooms have become a fact of school life The district has 1,282 portable classrooms at its 217 elementary school campuses. To accommodate all those classrooms in permanent buildings, the district would need to have the equivalent of nearly 40 additional elementary schools.