Children are usually big enough to use a regular seat when they are 8 to 12 years old. Before allowing your children to use the regular seat and adult seat belt, make sure the seat belts fit them. The shoulder belt should lie across the chest, not the neck or throat, says the American Academy of Pediatrics (AAP). The lap belt should lie across the thighs, not the stomach. Children should be big enough to sit so that their back is against the back of the seat and their feet are hanging down, with the knees bent. Until your child reaches this size, he or she should remain in a booster seat.

Call your child's doctor if your child has fallen or taken a blow to the head and briefly lost consciousness. Seek emergency medical help after a fall or blow to the head if your child is unconscious; is breathing abnormally; is bleeding from the mouth, nose or ear; has pupils of unequal size; is dizzy or confused; or is vomiting.

Caffeinated beverages also may cause sleep problems in children and lead to dehydration in hot weather, because caffeine causes the body to eliminate water. Also, children who drink lots of carbonated beverages—whether caffeinated or not—often aren't drinking enough milk, a good source of calcium.

According to the CDC's America's Children: Key National Indicators of Well-Being, 2009 survey, 19 percent of children ages 6 to 17 were overweight in 2006. In 1976, 7 percent of children ages 6 to 17 19 were overweight.

In the United States, the average age for a girl to start menstruating is 12. The start of menstruation—called menarche—cannot occur until a girl's entire reproductive system has matured.

ADHD doesn't interfere with intellectual ability. Many ADHD kids are highly intelligent and creative.