Well where I live here in Arizona, there is no longer a requirement for having a license for Concealed Carry within the state.
In Arizona, a person over age 21 may legally carry a concealed firearm or deadly weapon without a permit within the state, except for certain prohibited locations, and must disclose the fact to a law enforcement officer if questioned.
There is still a Concealed Weapons Permit for Carrying out of state within reciprocating states though, which I already have.
What I am advocating is the right, of the teacher and/or student (over the age of 21 obviously), on their own free will and cost, to educate themselves and obtain a license to specifically carry concealed within the grounds of a school or to extend their CCW for carry on school grounds or most publicly operated "gun free zones" with the exception from already armed guarded locations such as court houses, capitals, prisons/jails, etc. this would also not include any private property, since private property is excluded from such regulations.
Carrying a firearm on private property or in a private establishment where it has been forbidden by the owner or another person having lawful control over the property is not expressly prohibited by law, but is held to constitute misdemeanor trespass
This is something that can be done fairly simply. It would probably have to be state by state though. Although I do believe there should be a national CCW permit, similar to a LEO CCW card (which has to be renewed every year and in some states, a qualification is required each year), which someone qualified would be able to carry concealed in all 50 states, I do not think the infrastructure is there for this at the moment.