OAKLAND -- As students returned to classrooms in Oakland for the first day of school Monday, some concerns remained regarding the East Bay school district's teacher shortage.Masks were optional for Oakland Unified School District students as they came back to class. Of course, teachers are one resource that is anything but optional. "Right now, we are about 40 teachers short. So with that said, all of our classes are covered with subs at Individual schools," said Oakland Unified spokesperson John Sasaki. He noted that the district is currently hiring. Oakland Mayor Libby Schaaf paid a visit to Montclair Elementary to cheer...