A parent knows his child better than any other person and wants the best for that child. He can tailor his instruction to the specific needs and learning style of his child. A parent is extremely motivated to enable his child to succeed and will persevere to find solutions that work. Through avid reading, some people become real experts in the area of their child's special need. Flexible scheduling and presentation allow curriculum and teaching methods to be based on a child's learning rate and style.
Parents can teach to the child's strengths while working on the child's deficits.
The stigma of the child's being, say, removed from a classroom to be helped individually, or ridiculed by other children, is not there. In some instances, parents set different expectations for a child and find that he can achieve even more than he did in another setting. Character building can be a major focus. These are just a few of the many possibilities. Children may have limited access to some specialized equipment.