There are many different reasons that adults have not managed to learn the skill of reading. Before working with an adult to teach them to read, make sure they have had a good physical examination, including hearing and vision testing. The information gained from these tests can help a teacher be successful where others may have failed.
Testing is a big part of knowing where to start and what methods to use for each individual. It does not have to labelled a test, but a baseline must be established. Most non-readers have a vocabulary of sight words that can be used as a base. Most non-readers have also developed a lot of masking skills to hide the fact they can not read. These defenses need to be worked through and dropped.
Nonsense words are a great tool for checking phonics and understanding of how letters make words. It is not all there is to reading, but it is important to know how words are formed and how to decode them. Since the words are not real, true phonics is easy to teach and detect if the principle is understood.
Have the adult reader share an experience and record it. Use some of those words in reading assignments. They are familiar to the adult and that gives them one more decoding device. Guessing is a big part of reading. Many avid readers will assume they know the word from context, mark it for vocabulary later and move on to get through the assignment.
Adults have strong likes and dislikes. It is important to center the reading material on something the adult will enjoy reading, whether it’s old Westerns or magazines about sports. What is being read really is not as important as learning to read and being able to apply it in everyday life.
A millionaire from Montana confided in a teacher that he didn’t know how to read. He always forgot his glasses at meetings, so someone would have to read the information aloud. He would say that he wanted to review the material so he would record as they were reading. He has hundreds of coping skills and he was so good at it, none of the people he did business with had a clue. However, when his grandchildren wanted him to read, he would have to talk them into just telling them a story. That was his turning point and he was ready to read.
In conclusion, get to know the student. Teach sight words, vocabulary and phonics. Keep it personal and celebrate successes. Teaching adults to read is one of the most rewarding experiences a teacher can have.