San Francisco public school teachers could be on strike as early as next week after negotiations between their union and the school district have stalled. It would be the first teachers strike in the city in 47 years. “We’re anticipating folks are voting ‘yes,’” said Cassondra Curiel, the teachers union president, in reference to the proposed strike. Union members also want a new special education staffing model aimed at reducing caseloads and teacher turnover. It’s storming and they need to use it,” she said, referring to the school district.