AT 13, BIANCA STOOD A LITTLE OVER 5-FOOT-3 AND HAD LONG BROWN hair. So did another girl at her private middle school in San Francisco. While they were both in class one day in 2013, a staff member entered the classroom, walked over to Bianca, took her school-issued iPad, and left. Later, the eighth grader was told to report to the principal’s office, and everyone watched her go. Apparently, the other girl had sent a naked photo of herself to a boy in the class, “and the person who received that, their mom saw, thought it was me, and reported it to the middle school head,” says Bianca (a pseudonym for privacy reasons), who is now a senior in college. Bianca was upset, but she was also brazen, sometimes jumping…