This spring the U.S. Education Department reported that in the 2015-2016 school year, "nearly 240 schools ... reported at least 1 incident involving a school-related shooting." The number is far higher than most other estimates.
But NPR reached out to every one of those schools repeatedly over the course of three months and found that more than two-thirds of these reported incidents never happened.
Good for NPR for acting like real reporters.