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.
Teaching the subject to an older child may be a bit more difficult. There are many math problems out there that can be used to bring it down to their level. Using this subject in an everyday situation is a one idea. For example, tell a story that involves that child. If he goes to the store and buys a gallon of milk with a five dollar bill and the milk is only three dollars, how much money will he have left? Using word problems will help the child understand it more.