Teacher should be allowed to carry firearm
1. Teachers are targets too (obviously everyone is a target, depends on who is preying).
2. Everyone has the right to feel safe.
3. Teacher can be able to defend him/herself including the class he/she is incase of a robbery or any other criminal activity.
Of course the teacher must possess a gun license and the firearm should not be used for any other purposes in the classroom other self defense/protection.