Has arming teachers in Navasota ISD kept children safe?

The deadly massacre in Uvalde is reigniting the big conversation about how to keep kids in school safe. Navasota ISD has been letting certain staff members carry concealed weapons on campus for the past few years. We learn how the ‘guardian plan’ has been working.

EXPLAINER: Social media and the Texas shooter's messages

Could Facebook have known about ominous direct-message threats made by a gunman who Texas authorities say massacred 19 children and two teachers at an elementary school? Could it have warned the authorities?