Meet me by the bicycle rack after school!!
Just kidding. I think you are looking at the wrong thing. In this case, the numbers don't tell the story; in fact, they provide misleading information.
Israel is surrounded by enemies who are constantly trying to destroy anything they can and kill as many people as they can. That's a bit different than the US who's enemies, for the most part, are separated by oceans or thousands of miles of land.
If we take the event that triggered this debate, the massacre at Sandy Hook Elementary, and we envision Connecticut not as a state in the United States, but as a sovereign nation surrounded by other sovereign nations that may be hostile to it, does that change the picture for you?
IMO, if we take the cut and dry numbers you calculated to provide another number for the solution, we ignore the fact that those numbers represent a person. People are unpredictable. On any given day, Egypt, Hamas, Lebanon, Syria, or Jordan may, individually or collectively decide to launch an attack against Israel. That's NOT the same thing as a lone, mentally disturbed individual launching an attack against small children in an unarmed school.
So, I believe that the comparison between 8 children murdered in school in the past 10 years versus 323 children murdered in school speaks volumes about having armed teachers.
The kid that did the shooting wasn’t an enemy of anyone, was he? I think that Israel just has different kids than we do in the US, as do a lot of countries.