Some possible triggers for children with a sensory processing disorder are bright lights, uncomfortable clothing, gentle touches like hugging, wearing shoes, certain odors and being dirty. To avoid some of these triggers, a teacher might adjust the lighting in the room, avoid perfume and have wet tissues available for easy clean-up. She might also make exceptions for the child, such as allowing him to take his shoes off, or to sit in the middle of the classroom, minimizing noises from outside and the hall.
Everyone wants respect and children with sensory issues are no different. Some of their issues may seem silly to an observer, and it's tempting to push the child to do things she doesn't want to do. However, this might result in a meltdown. Instead, offer the child alternatives or simply ignore the problem. For example, if she doesn't want to finger paint because she doesn't like the feeling of paint on her fingers, let her use a paintbrush instead; if she won't eat carrots because she doesn't like how they feel in her mouth, simply let her be, rather than making a big deal out of how healthy carrots are and how she should "just try one."
Some children are sensory seekers. This child might be a little more "hyperactive" than others. To help him fit in the classroom, the teacher might give him special tasks to keep him active and engaged. She might also allow him to hold a special toy that he can squeeze or stroke or let him chew on a special chewing toy.
There's no one-size-fits-all approach to dealing with children with sensory processing problems. The best way to deal with a child in the classroom is to talk to the child's occupational therapist. The therapist can explain the child's behavior and offer suggestions that the teacher can use to help the child feel more successful.