The exercise was hosted by First Draft, a research group that trains people to understand and outsmart disinformation. Sitting around communal tables, we assigned ourselves the roles of reporters, editors, social media managers and a communications director. A tip came in through e-mail: Did we see the rumor circulating on social media that people can vote by text message? Then a new tip appeared: someone on social media said there was an active shooter at her polling place. I had spent the previous year researching digital disinformation and producing articles on its history, techniques and impact on society.