When it comes to stuff to put in your kid's school backpack, I'd spend a little time trying to make sure your school actually let's your kid have that pack while in class. All the elementary schools I've been in have a desperate cloak room or hallway where coats and packs are kept. If we were in tornado or earthquake territory, I'd want my kids to keep the packs, and emergency stuff, on their chair backs.

That said, I'm still working on getting our schools to let the kids keep a sweater or jacket in their chairs AND let them grab those in a fire alarm situation. Most schools don't even seem to have a blankets to keep the kids warm and dry I've seen fire drills in the fall and winter, where the kids are standing around in a cold rain waiting for the all clear. In a real situation, emergency services might show up with stuff if the event was on a small scale, but I prefer my kid to be a less dependant than that.