SAN FRANCISCO — The black and yellow signs were hard to miss, their message spelled out in English and Cantonese: “Vote YES to Recall the School Board.” Volunteers with the Chinese American Democratic Club urged shoppers to get registered for the Feb. 15 election, telling them why three members of the city’s school board — all Democrats — needed to be removed from office. Yung Chen, 73, was already convinced. “Martin Luther King’s speech, I believe in that: Don’t judge people by racers ,” he said. His grandson, he explained, nearly missed out on a spot at the high school...