Actually, Boots, there indeed HAVE been cases of school classrooms with armed students.  A now deceased acquaintance of mine related how he and his classmates were permitted to arm themselves during the Kenyan Mau Mau Rebellion in the early 1950s.  I do recall his weapon of choice was his dad's high-power .303 Lee-Enfield "varmint" rifle.  He recalled that some of his chums availed themselves of fully automatic 9mm STEN submachine guns if their families had one.  Now, to be sure, the guns weren't kept at their desks during class, but WERE kept loaded and propped against a convenient nearby wall.

I do not recall him describing any accidental discharges or murders, robberies, or other criminal mischief due to these loaded guns at school.  

Being you, Boots, you may dismiss this as just white boys making a show or taking advantage of a privileged station in the Kenyan society of the time.  But that's not germane any pro or anti gun sentiment expressed here correct?