Given the proper training, the gun would never have shown up in school. Most kids that I know whose parents own guns have taken the necessary training courses, and wouldn't think of nringing the weapon into school. This is another case of parents letting their children go unchecked.
But the school's teach safe sex, so they must be okay....
How about a Gun Safety course? What Not to Do.
Training is absolutely necessary but not absolute insurance against stupidity.
Raising teenagers these days is like herding cats. You give them the tools and the proper value system and hope they learn from other people's mistakes. Some don't.