A small school district in Texas that operates a single K-12 public school has authorized teachers to carry guns.  For employees to carry a pistol, they must have a Texas license to carry a concealed handgun; must be authorized to carry by the district; must receive training in crisis management and hostile situations; and must use ammunition designed to minimize the risk of ricocheting bullets.  

A group of parents is upset about the fact that guns will be present in the school and has asked you whether any constitutional challenge to the gun policy is possible.  In considering the answer to this question, you should consider the following provisions of the Texas Constitution:

Every citizen shall have the right to keep and bear arms in the lawful defense of himself or the State; but the Legislature shall have power, by law, to regulate the wearing of arms, with a view to prevent crime. (Article 1 - BILL OF RIGHTS - Section 23 - RIGHT TO KEEP AND BEAR ARMS)

A general diffusion of knowledge being essential to the preservation of the liberties and rights of the people, it shall be the duty of the Legislature of the State to establish and make suitable provision for the support and maintenance of an efficient system of public free schools. (Article 7 - EDUCATION - Section 1 - SUPPORT AND MAINTENANCE OF SYSTEM OF PUBLIC FREE SCHOOLS)

Texas gun laws permit the school district to adopt such a policy:

§ 46.03.  PLACES WEAPONS PROHIBITED.  (a)  A person
commits an offense if the person intentionally, knowingly, or
recklessly possesses or goes with a firearm, illegal knife, club,
or prohibited weapon listed in Section 46.05(a):
        (1)  on the physical premises of a school or
educational institution, any grounds or building on which an
activity sponsored by a school or educational institution is being
conducted, or a passenger transportation vehicle of a school or
educational institution, whether the school or educational
institution is public or private, unless pursuant to written
regulations or written authorization of the institution;
        (2)  on the premises of a polling place on the day of an
election or while early voting is in progress;
        (3)  on the premises of any government court or offices
utilized by the court, unless pursuant to written regulations or
written authorization of the court;
        (4)  on the premises of a racetrack;                                         
        (5)  in or into a secured area of an airport;  or                            
        (6)  within 1,000 feet of premises the location of
which is designated by the Texas Department of Criminal Justice as a
place of execution under Article 43.19, Code of Criminal Procedure,
on a day that a sentence of death is set to be imposed on the
designated premises and the person received notice that:
            (A)  going within 1,000 feet of the premises with
a weapon listed under this subsection was prohibited;  or
            (B)  possessing a weapon listed under this
subsection within 1,000 feet of the premises was prohibited.
    (b)  It is a defense to prosecution under Subsections
(a)(1)-(4) that the actor possessed a firearm while in the actual
discharge of his official duties as a member of the armed forces or
national guard or a guard employed by a penal institution, or an
officer of the court.