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.
Another important thing you must do as a parent is ensure that you are helping them with their homework. Make sure that every night they get homework, they spend time away from their friends and the television and sit down to concentrate on their work. This might seem daunting at first, but if you spend time with them and help them when they need your help, you can stress the importance of studying, and how it doesn't have to be as daunting and as boring as they think. Help them with their math worksheets every evening, whether they're working on the multiplication table or division, so that they can continue to succeed during their school career.