http://www.theguardian.com/us-news/2015/oct/27/south-carolina-sheriffs-deputy-on-leave-after-forceful-classroom-arrest
So teacher asks student to put cell phone away and comply with class room conduct.
Student refuses.
At teacher's request, principal asks student to put cell phone away.
Student refuses.
Principal insists student put phone away or leave school grounds.
Student refuses thus satisfying the elements for felony trespass.
Cop called in, cop asks trespassing student to vacate school.
Student refuses.
Cop observes felony trespass, and warms student he will remove her if she insists on trespassing.
Student refuses.
Cop physically removes felon from class
room, thus protecting other students from the unpredictability of felon.
How could cop do anything better?