Don't think the "lazy teacher" argument applies here.
I know. Class seems more important than a terrorist threat on the kids. I'm defending the kids, not the teacher who may have to work a few extra days into his 3 month summer vacation.
If LE says there's a credable threat, get the kids out of there. If parents are concerned, it's because they're doing it out of love for their kids. Kids first. Government funding or vacations later.