It’s not really the case, as you may have seen reported elsewhere, that there have been 18 school shootings in the United States this year. That data point comes from a gun-control-advocacy organization called Everytown for Gun Safety and includes any discharge of a firearm at a school — including accidents — as a “shooting.” It also includes incidents that happened to take place at a school, whether students were involved or not.
Perhaps these meet your standard for a school shooting, but generally, the term refers to something more specific: the targeting of students or teachers at a school. By Everytown’s standard, there has been a shooting every 2.5 days this year. Using a stricter standard, there have been at least seven school shootings in 2018 — more than one each week. Shootings near New Orleans and Los Angeles. Shootings in Kentucky, Arizona and Texas. And, on Wednesday, a shooting in Parkland, Fla., that has left 17 people dead and an undetermined number wounded (as of writing).