I do not consider that an effective method for the following reasons.
A. The example of Columbine High School, where the on-site police officer ran away from the terrorists there, demonstrating that there are police less motivated to protect pupils that such as the Sandy Hook school staff who threw themselves between the shooter and those babies to act as bullet absorbers----To NO good effect!
B. The many rooms, multiple floors and long, often bent, hallways in many schools make one armed person of limited uses even if in close proximity to the site-of-maximum danger.
C. The moneys to be spent on such much too limited protection would be much better applied to the plan described below.
2. Such training should, by NRA-certified or other qualified instructors, probably not required more than 20-hours of hands-on training (On top of 2/3 hours of safety instruction) and must involve qualification every two-years at close-combat ranges [Considering the track record of the New York PD at the "Empire State Building Shootings", it would be well to insure that all instructors are, themselves, qualified shooters);
3. "Force-on-force" training, with paint ball guns, is recommended to provide the needed and painful lessons;
4. Such qualified school staff could buy their own guns (Tax deduction) or be reimbursed for such;
5. Qualified school staff would be required to CCW them while on duty;
6. Federal law could be satisfied by having the local Sheriff swear them in as "Special Deputies", with authority limited to the assigned school and grounds;
7. Where laws allow, those persons could obtain CCW licenses/permits and take their weapons home, otherwise a gun safe could be provided; And,
8. The office staff should have access to a carbine in such a safe as can be opened by biometric means.
Considering the NRA's very long support of citizen marksmanship, it would have been better for you to support the second plan provided above. Certainly, most teachers will demonstrate a more parent like desire for the protection of THEIR children than some peace officer, no matter how motivated. Being distributed throughout schools, such armed staff would provide a "clear and present" measure of protection well beyond that of one peace officer.
PS---Si Vis Pachem Para Bellum!