Oakland teachers have set a one-day strike for March 24, an action that could shut down schools unless district officials make major concessions at the bargaining table, union officials said Wednesday. The strike could leave parents scrambling for child care and force the financially strapped district to decide whether to keep schools open with administrators and support staff in classrooms or tell students to stay home. Teachers who represent the union at the school sites cast the strike votes this week, and the result was overwhelmingly for the one-day walkout, an action the union's general membership, which includes 2,700 teachers,...