In the widest sense of dual coding it is using two pieces of different representations of an information to create a memory of a subject. Rossie talks about his own Dyslexia and the barrier that it was for him during his school days, in his story, which is told in this video, he explains the lightbulb moment where he switched tactics and move to a fun based learning style, comics.  You will be amazed on the progress this simple yet effective change made to his entire life.