Do you have any evidence at all to support your position that this will lead to more school shootings? Because I can cite resource to refute that position based upon existing schools that permit weapons on campus.
The following is from http://concealedcampus.org
(citations to support this comment are found on that cite).
"Since the fall semester of 2006, state law has allowed licensed individuals to carry concealed handguns on the campuses of the nine degree-offering public colleges (20 campuses) and one public technical college (10 campuses) in Utah. Concealed carry has been allowed at Colorado State University (Fort Collins, CO) since 2003 and at Blue Ridge Community College (Weyers Cave, VA) since 1995. After allowing concealed carry on campus for a combined total of one hundred semesters, none of these twelve schools has seen a single resulting incident of gun violence (including threats and suicides), a single gun accident, or a single gun theft. Likewise, none of the forty ‘right-to-carry’ states has seen a resulting increase in gun violence since legalizing concealed carry, despite the fact that licensed citizens in those states regularly carry concealed handguns in places like office buildings, movie theaters, grocery stores, shopping malls, restaurants, churches, banks, etc. Numerous studies*, including studies by University of Maryland senior research scientist John Lott, University of Georgia professor David Mustard, engineering statistician William Sturdevant, and various state agencies, show that concealed handgun license holders are five times less likely than non-license holders to commit violent crimes."