You may want to let them try and work out how long it will take you to travel somewhere when you get in the car, by telling them what speed you'll be traveling and how far away your destination is.
This is one subject that does not go away once graduation is over. It is a subject that everyone is faced with on a daily basis. One may not realize it, but everyday math is out there, whether it is at the local grocery store or in the classroom. Keep the subject fresh in the mind, and the person will succeed in life.