The Missouri state legislature stirred up a hornet’s nest last year when it passed a law prohibiting teachers from communicating privately with students on social media. Without much debate, the bill passed easily and the governor promptly delivered his signature. But educators complained that the law would needlessly interfere with how they interacted with students and civil liberties advocates said it also violated the First Amendment. Lawmakers conceded they may have overreached and went to work on repealing parts of the law. By the fall, they had removed the most controversial provision, which barred teachers from using websites that allow “exclusive access” with current students or former students who are 18 or younger.