Cameras in classrooms isn't the answer.
In most of these cases it's down to a poor attitude towards disabled students and general abusive *@#$ who don't get nearly enough in the way of punishment (plus schools that allow this to go unchecked, and continue to hire these sorts of people even after they've been shown to abuse kids). As with any other area where vulnerable people are involved; disabled, elderly, children, there aren't tight enough regulations or enough checks being done to ensure no one is at harm. Camera's won't cure this particular evil of society.
Don't get me wrong, if I have kids who end-up in 'special education' I'll be watching them like a hawk if not only for the fact such education remains painfully inappropriate in supporting and respecting disabled kids, and if I saw any change in my child's behaviour I'll be strapping them up with microphones and cameras in a heartbeat.
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Bloodheart
Good-looking girls break hearts, and goodhearted girls mend them.