Because my children will never be asked to stand up and describe what they don't like about a person, then participate in a vote on whether or not that person should be allowed to remain in the classroom.
A teacher in St. Lucie, Florida, did just this in her kindergarten class. As a five-year-old boy, who is in the process of being diagnosed with Asperger's Syndrome, was forced to stand at the front of the room, his classmates were each given a turn to say what they disliked about him. They described him with words including "disgusting" and "annoying," then voted 14-2 to make him leave the classroom; he spent the rest of the day banished to the nurse's office. The Florida state attorney's office says this treatment does not qualify as emotional abuse and is not pursuing criminal charges against the teacher. The district says it is "investigating" the incident (which teacher Wendy Portillo has admitted) but has not yet taken any action.
The boy has refused to return to school since then; and if I were his mother, I can't imagine why I would even try to make him go back.
Since our children are not (surprise!) completely socially isolated, we attend classes two days a week at Village Home. One of the most heartening things I've observed in our time there is the way that all kids–the loud ones, the quiet ones, the ones of varying cognitive and social ability, the ones who I am pretty sure have been or could be diagnosed as autistic–are treated as just part of the group. There are special friendships, sure; but I haven't seen poisonous cliques, I haven't seen shunning, I haven't seen my kids or anyone else's deliberately leave someone out because of personal differences.
And I know when I tell my boys about this little boy in Florida, they will be as horrified as anyone should be. As horrified as the students in that class should have been. Because no one's ever told them that you have to do what the grownup says just because the grownup is a grownup. Because no one's managed to convince them yet that different = bad and that cruelty = a good way of dealing with difference. And I hope to god that no one ever can.