An elementary school teacher faces up to 10 years in prison for taking an extreme measure with an autistic student. Kirsten Joelle Barnett has been charged with injury to a child after she bit a 4-year-old on the cheek.

School employees reported that the child was left with a "swollen bite mark" after the incident. Barnett was immediately sent home and the police and parents were alerted.

A teacher biting a student, especially one with special needs, is almost unthinkable. So why has it happened so often? Barnett isn't the first teacher to be arrested for biting a student.

In late 2015 a teacher in Florida was arrested after biting a 8-year-old special needs student. A police report from the time detailed the events.

Karen Williams, a previously well respected 3rd grade teacher, had put the child in a bear hug after he began acting out. In an attempt to get away he bit Williams on her right hand. The teacher then bit the child on the back "for like a minute."

She was charged with child abuse although those charges were later reduced to culpable negligence that inflicts injury. She was fired and never saw any of her students again.

Twice is bad, but surely these two times are the only instances right? Wrong.

Perhaps most shocking of all is the case in Washington DC, where a preschool teacher is accused of biting a 13-month-old on the shoulder after he bit another teacher. Police say the bite was hard enough to leave a mark on the toddler's shoulder.

Earlier this year another teacher was arrested, this time in South Carolina, when she bit an 11-year-old child who had stolen his friend's hat. Melanie Johnson allegedly witnessed the theft then grabbed and bit the boy after he refused to give back the hat.

The victims mother told police that her son had a visible bite mark on his neck.

Yet another student in Florida was left with a bruise behind his ear after his teacher bit him during the lunch hour. The student allegedly told his mother that the teacher was mad that he was wearing his hood up while eating.

The bite was hard enough to leave a bruise visible when the principal took a photograph for evidence.

"You never put your hands on a child," said Tasia Johnson, the boy's mother. "That's not okay."

It should be common sense, but with the alarming rate at which teacher's are getting charged, it seems that the idea you shouldn't bite children isn't common place.