You understand that a lot of communication in that scenario can, at worst, lead to crucial misinformation about what's going on and, at best, is unnecessary, don't you?
Obviously, these shootings happen, but the solution is not to arm each student with a cell phone, just as it sure as hell isn't to arm each teacher with a firearm.
The detrimental effects of cell phone usage in the classroom are well documented and plain as day if you just walk into a high school or middle school lesson. Even with highly engaging teachers and lessons, there are kids who slip through the cracks because nobody can compete with the newest fad app designed to melt a child's brain and possibly drain their parent's bank accounts.
This move addresses a significant issue within our school system. Addressing gun violence in the US is a very complex issue that needs to be tackled through a lot of different fronts. Kids having smart phones in school will not address that issue.