UUmmm, a gunman wont be shooting at the backpack. And most of these shootings happen when the kids are in classes, sitting down with no focus on when a shooting gonna happen. So most likely when a shooting occurs, they'll be there in panic mood and dont even remember the bag. Plus, a gunman is always facing the victim and he'll more likely aim for somewhere not covered.

But still, its a starter, so thumbs up to those dads