There are many variations of behavior and intelligence in the subgroup of children diagnosed with ADHD, just as there are in the general population. Some children are more active than others, and some merely have difficulty focusing on the task at hand. Unfortunately, the trend today is to label children who may only be "different" as having a learning disability such as ADHD.
The structure of many elementary classrooms is one that promotes chaos versus calm; children frequently are arranged in groups, at "tables", and are expected to work cooperatively, quietly, and more independently than in years past. Children are not being given enough basics, enough drills, or enough memorization to train their minds in order to meet these expectations.
ADHD children in particular need balance and structure and rules. They need them at home, and even more so in school in a louder, more confusing environment. ADHD children need clear consequences for misbehavior and clear direction for sometimes even the smallest tasks.
A child diagnosed with, or suspected of having, ADHD, cannot handle the "typical" hectic schedule of kids today He needs time to be himself, time to relax from the expectations of the majority of society. Furthermore, he often needs more time to be made aware of time itself and the accompanying activities that he must take part in.
A very active ADHD child needs more than the normal amount of rest; his brain and his body are in overdrive, and this can take a toll. An average grade-schooler requires 8-10 hours of sleep; an ADHD child needs to be resting on the high end of that recommendation. He also needs more verbal notice that one activity is ending and another beginning; his brain needs time to wind down from the one and gear up for the next.
An ADHD child is over stimulated, and must learn to discipline himself even more so than the average child. To this end, he must have a set schedule with few variables so he can feel more in control of his environment. This makes it much easier for him to focus and concentrate. A certain time and place for homework with the age-appropriate assistance is especially beneficial.
Medication, while hotly debated, is also a tool when used properly. Rather than over-medicating, a small dosage of a drug such as Ritalin can enable a child to focus and achieve. This results in better control, better self-awareness, and improved accomplishment.
Children with ADHD simply require more downtime, more individualized attention, and more scheduling and routine than the average child; with these things in place, they can certainly succeed both in the classroom and in their daily lives.