Since your son has ADD (or perhaps ADHD), he may not be able to focus and sustain attention long enough or consistently enough to benefit from the special education he is getting. It's almost as if his "attention switches" are going on and off. This can be caused by the intermittent underproduction of chemicals called neurotransmitters that allow electrical impulses to travel smoothly and swiftly from the end of one nerve (neuron) in the brain to another neuron. Medications (such as Ritalin) that are used to treat ADHD stimulate the production of these chemicals. This helps to bring them into a more normal balance so that the brain works more efficiently. If you are not comfortable with the idea of medication, talk to your child's pediatrician about it to get more information. You can also learn more about ADHD, medication and other interventions by pointing your Web browser to Chadd, LDOnline, etc.
Before considering medication, however, it's important to find out if your son's teachers are doing all they can to help him focus and sustain attention in class. For example, they should be doing things like using his name or touching his desk (as a cue) before introducing a topic or concept. Having two kids discuss a concept or practice a new skill helps to insure that the student with ADHD is focusing on the task.
If your child's teachers can't figure out why his reading skills are not advancing, they have an obligation to seek consultation about this. Most schools have a child study team or teacher assistance team that can provide input to teachers working with students who are not making progress. It may also be time for a re-evaluation of your son's abilities. This is especially important if the teachers do not understand the causes of his reading difficulties. For example, does he have difficulty hearing the difference between sounds (phonemic awareness), or does he have poor short-term visual or auditory memory, which would make it difficult for him to remember what he has just seen or heard.
Your son may need additional specialized intervention from a teacher trained in reading disorders. This should happen soon, since he's already feeling like he's different from other kids. Effective intervention can help him achieve more success with reading and head off problems with self-esteem.