Every state varies
Kansas has laws that allow unlicensed person to pick-up or drop off children at school with a gun in their car.
KSA 21-4204
(5) possession of any firearm by any person, other than a law enforcement officer, in or on any school property or grounds upon which is located a building or structure used by a unified school district or an accredited nonpublic school for student instruction or attendance or extracurricular activities of pupils enrolled in kindergarten or any of the grades 1 through 12 or at any regularly scheduled school sponsored activity or event;
(6) refusal to surrender or immediately remove from school property or grounds or at any regularly scheduled school sponsored activity or event any firearm in the possession of any person, other than a law enforcement officer, when so requested or directed by any duly authorized school employee or any law enforcement officer; or
(7) possession of any firearm by a person who is or has been a mentally ill person subject to involuntary commitment for care and treatment, as defined in K.S.A. 59-2946, and amendments thereto, or persons with an alcohol or substance abuse problem subject to involuntary commitment for care and treatment as defined in K.S.A. 59-29b46, and amendments thereto.
(b) Subsection (a)(5) shall not apply to:
(1) Possession of any firearm in connection with a firearms safety course of instruction or firearms education course approved and authorized by the school;
(2) any possession of any firearm specifically authorized in writing by the superintendent of any unified school district or the chief administrator of any accredited nonpublic school;
(3) possession of a firearm secured in a motor vehicle by a parent, guardian, custodian or someone authorized to act in such person's behalf who is delivering or collecting a student; or
(4) possession of a firearm secured in a motor vehicle by a registered voter who is on the school grounds, which contain a polling place for the purpose of voting during polling hours on an election day.
The Federal law does exempt a licensed person from the 1,000 foot GFSZ [if you're licensed in the state where the school is] {that needs to be changed, shall issue and reciprocity was not an issue when the federal law was written}.
Most LEO, many DAs know no more than you do, they will tell you "common knowledge" and that is often wrong.
http://www.ksag.org/files/shared/KPFPA Statutes (75-7c01 et seq.) 2009 Update.PDF
Kansas CCH law allows licensed carry on school grounds unless posted with the Kansas gunbuster sign. There are a lot of FAQs on the KS AG site
http://www.ksag.org/content/page/id/90