It’s normal for children to occasionally forget their homework, daydream during class, act without thinking, or get fidgety at the dinner table. But inattention, impulsivity, and hyperactivity are also signs of attention deficit hyperactivity disorder (ADHD), sometimes known as attention deficit disorder or ADD.
https://www.helpguide.org/articles/add-adhd/attention-deficit-disorder-adhd-in-children.htm