Children with attention-deficit hyperactivity disorder (ADHD) find it unusually difficult to concentrate on tasks, to pay attention, to sit still, and to control impulsive behavior. Some children with ADHD exhibit mostly inattentive behaviors and others predominantly hyperactive and impulsive. But the majority of those with ADHD have a combination of both, which can make it very difficult for them to function in school, and create a lot of conflict at home.