"He's the perfect choice at this critical time for education," Schwarzenegger said of Bersin, who served two years on the California Commission on Teacher Credentialing. Bersin, 58, offered a glimpse of his hard-hitting approach at the news conference. Standing next to the governor and speaking in a relaxed but firm tone, Bersin did not shy away from taking on teachers unions. "It's very important that we find common ground for what our kids need, not what's good for the union," he said. "This has to be premised on what's good for children." Barbara Kerr, president of the California Teachers Assn.,...