I don't BLAME her, but she should at least be warned that NO ONE outside of a SCHEDULED and PLANNED demonstration, should walk into her classroom, pull out a gun, and start passing it around to the kids.I don't blame the teacher one iota if s/he was ignorant of all things gun and trusted the implied safety/skill/judgment of an "official".
It's what we get beat over the head with from our government all the time; "Respeckt mah authoritay!" She obviously thought someone supposedly "trained" would know what they were doing.