With schools under increasing pressure to improve test scores, Mount Diablo High School has resorted to a new way to motivate students: by race. The Concord campus on Friday held separate assemblies for students of different ethnicities to talk about last year's test results and the upcoming slew of state exams this spring. Jazz music and pictures of Martin Luther King greeted African-American students, whereas Filipino, Asian and Pacific Islander students saw flags of their foreign homelands on the walls. Latinos and white students each attended their own events, too, complete with statistics showing results for all ethnicities and grade...