A child who seems to be fidgeting, leaving his seat at school or the dinner table, climbing excessively on furniture or desks, and talking too much, and is also described as having no "off" switch, would be diagnosed with Hyperactivity, it is often caused by a medical condition called ADHD. Children who are hyperactive not only move their bodies a lot, their brains also have a hard time reassuring themselves. There are steps you can take to help manage hyperactive behavior at home and at school.