FOREST GROVE, Ore. (AP) — A pair of Oregon school districts were intent on identifying warning signs that students might be contemplating a campus shooting when they stumbled on a threat far more pervasive yet much less discussed — sexual aggression among classmates.

So the districts adapted the same early-intervention approach used to handle potential school shooters: Based on observations or tips, staff now quietly keep an eye on kids they worry are sexually aggressive. The school enlists parents to understand why the child is acting out and intervenes if behavior threatens to escalate, whet...