Tell them how your experience with autistic children and special ed kids have taught you tremendous patience and the ability to be creative in handling them. Let them know that your special ed background makes you the perfect candidate in that you can handle just about anything that comes your way, as it takes a very special person to be able to effectively work with these kids. Your years of experience has let you know just what the job entails and has allowed you to grow as an individual and has given you a special appreciation for your role as an aid in the classroom. You know how you can best help the teacher and be the teacher's best friend in that room.