We at home have a harder time with behavior, as it is draining at times to be continuously understanding of his level of activity. He is not, per se, a behavioral problem, but I read this may lead to behavioral problems as he gets older. It is hard for his stepfather to understand at times that his responses and reactions are a symptom of his disorder. If you can make sense of this please give me an answer.
Because ADHD is a neurologically based condition, many children are more successful if they take medication that helps them use the tools and techniques that teachers and parents suggest. It's sometimes helpful to use a leaky bucket example: children with ADHD have a hard time holding onto things that they learn (the water runs out of holes in the bottom of the bucket). It often seems like they can't focus long enough to learn, and when it looks like they have "gotten it," they often lose it the next hour or the next day. Medication can help seal up the holes in the bucket, so to speak, so parents and teachers won't have to keep reminding the child over and over to do something.
You are right to be concerned about the impact of constant reprimands on a child's self-concept and his behavior. For that reason, it's important to pick one or two specific behaviors to work on intensively in a positive way, so that the child (and his parents and teachers) can see that he is capable of changing his behavior. Unless parents and teachers understand the condition and explain its impact to the child, and what you are all going to do about it, he'll quickly develop the attitude that he's a "bad kid." This can and must be avoided. Unless there is a conscious effort to help the child to demonstrate positive behaviors, he will keep hearing things like: "How many times do I have to say..." or "What's WRONG with you?" These messages do not acknowledge that ADHD is a real and treatable condition. These messages reinforce the attitudes of blame and shame that are too often associated with ADHD. We'd never say such things to a person whose blood pressure went up, would we? Parents and teachers need to learn as much as they can about this condition, which affects so many children. I'd suggest that you visit CHADD and ldonline.