It’s crazy they actually do think that arming teachers is a good idea. That’s just introducing even more guns to the classroom and increasing the chance of an accident happening.

As for his dad owning the AR-15 Thomas Matthew Crooks used to shoot Trump, I found this article:

Crooks used an AR-style rifle, which authorities said they believe was purchased by his father. Kevin Rojek, FBI special agent in charge in Pittsburgh, said that investigators do not yet know if he took the gun without his father’s permission.

I guess it might depend on if his father gave him permission or not. Even then, Thomas Matthew Crooks was also an adult, so I am not sure laws pertaining to how well the gun was secured will apply.