I don't understand why people do that nor do I understand people who stand there and let it happen. I was so lucky as a child the only bully I had to deal with was my third grade teacher....yeah the teacher who kept telling the class I needed to be sent to an institution. Thankfully most students still treated me the same. But for an entire school to do that!
Have you checked into the PA(protection and Advocacy) for your area? They are legal advocates for disabled people and do a lot of work on getting children's needs met. Google; protection and advocacy (name of your state). it's a federal organization and there's one in every state.
Sorry I forgot they changed the name to ; DR( disability rights) so for you it would be DRA disability rights Arkansas.