The California State Teachers' Retirement System (CalSTRS) is asking Facebook to expand its board by adding a few women. As it stands now, the board is all male. The CalSTRS corporate governance director, who happens to be a woman, wrote to Facebook founder and CEO Mark Zuckerberg arguing that company investors and employees could benefit from a few more diverse opinions. CalSTRS had hoped Facebook would add more board members before its initial public offering, though that clearly didn’t happen.