The idea is that two or three teachers per school would be allowed to carry concealed-carry firearms and would be given training in their use in an active shooting situation.
It may surprise many Texans to know that the state already allows some teachers to carry firearms to school under the 2013 Protection of Texas Children Law (HB1009). The law designated a subset of law enforcement officers called School Marshals, similar to Air Marshals that guard some airline flights. Any employee of a school, teacher or staff, could volunteer as a School Marshal.
The criteria to become a School Marshal are rigorous. A volunteer has to undergo mental health evaluation and then an intensive training program that includes firearm proficiency and active shooter simulations and classroom instruction. Firearms have to be stored in a safe, accessible only to the designated School Marshal. The program is optional for Texas school districts, and not all participate.
Even before the law was enacted, teachers and staff were allowed to conceal carry on school grounds under certain circumstances since 2008.
According to Channel 5, the NBC affiliate in Dallas-Fort Worth, [one member] of the Texas State Teachers Association takes a dim view of the School Marshal program. He suggested that teachers should secure their classrooms and concentrate on keeping their students safe rather than engaging in gun battles with school shooters. However, proponents of the program maintain that the School Marshal program provides schools with an extra layer of protection during the first critical minutes before law enforcement can be summoned to deal with a school shooting situation.