Many dyslexics find spelling to be very difficult. One approach to addressing this difficulty is to call more than the sense of sight into play when working on spelling. This is called a multisensory approach. An example of this is: a child spells the word aloud as they trace the letters with their finger in a tray of cornmeal. This activity involves hearing (as the child spells out the word); touching (as the child spells it in the cornmeal); as well as seeing (letters in the cornmeal). Another example of a multisensory approach to spelling is moving plastic letters on a table top as a child says the sounds and arranges the letters.
If your child is in a school system and has been diagnosed as having a learning disability due to dyslexia, he probably has an Individual Education Plan (IEP). This plan addresses the most effective teaching strategies that will help him succeed in school.
If your child does not have an Individual Education Plan, you need to become your child's advocate. Make sure that teachers understand the degree to which your child is affected. Also, tell your son's teachers what strategies have been helpful in the past so that they know to use these strategies with your son.