 This is a test to find out if you know it all when it comes to children. Name one of the leading killers of U.S. children age 1 to 13. What's the best way to protect children in a car crash? At what age and size should a child start using a booster seat? Don't assume you know it all when it comes to car seats for your child. Go to safercar.gov slash the right seat and know for sure. Brought to you by the National Highway Traffic Safety Administration and the Ad Council.