PUT THEIR MONEY WHERE YOUR MOUTH IS
An allowance can be as handy a tool for fostering charity as it is for teaching other aspects of money management. Peggy Houser, a Denver financial planner and author of How to Teach Children About Money, advocates starting an allowance system as soon as your child starts school (or even earlier if you think he can handle it) and dividing the weekly dole into three parts, each clearly earmarked for a specific purpose: spending, saving, and sharing. Explain that the sharing portion is to be used for gifts to charity, and couple your explanation with a simple statement of your philosophy on the subject, such as "Our family believes it's important to share our good luck with people who are less fortunate."
The exact percentage of the allowance you apportion to charity doesn't matter; what is important is simply to incorporate giving into the child's budget. "The goal is to make giving money to those in need a routine," says Houser.
What you encourage your child to do with the money is key too. Instead of simply giving cash to a worthy organization once he has accumulated a reasonable amount, suggest that he use the money to buy a toy for a poor child or socks for a homeless person or some other item needed by someone in serious straits. Then take him to deliver it.