On any given workday, Marin County’s school resource officer might read with a class, respond to a weapon on campus or give perspective to a troubled child. “The only thing I know is that it is going to be different from the day before. No two days are the same,” said Deputy Josie Sanguinetti, the single school resource officer for the Marin County Sheriff’s Office. “If I don’t have anything that’s of safety concern, then…