Cynthia Barnard writes:

Here is a suggestion I read about a couple of years ago for Chanukah (I regret that I do not recall the author and so cannot give credit!).

Each night, give each child a check for $10, and invite her/him to fill in the recipient. Collect all those charity solicitations that fill your mailbox for the months before the high holidays and the winter holidays, spread 'em out on the dining room table, and get the kids to think about where they want to give "their" tzedakah. The final part is to insist that they write a short note to the recipient explaining why they are sending their gift to that organization. You could write a "form" letter on the computer, with the background of how and why your family is doing this, and have the kids just fill in the reason they chose that charity.