"Hopefully, it will be second nature for them when they're grown up," says McCarter, a mother of three in Greeenville, S.C. "I think it's very important. I think it teaches them to be appreciative of the things that people do for them."

Although it sounds simple enough, in our harried lives, writing thank-you notes is often a back-burner thought when it comes to mentoring our children, says Ernestine Whittenberg, program manager at Dunbar Child Development and Family Learning Center in Greer, S.C.

"We will have it in our heads to do it, but then we get so caught up in just the everyday things we have to do that we will put it off, and before you know it, two weeks have passed, three weeks. And then you think it's really too late," Whittenberg says. "But it's never too late."

The benefits are more far-reaching than you might realize, says Cindy Post Senning, co-author of Emily Post's "The Guide to Good Manners for Kids" (HarperCollins, $15.95) and co-director of the Vermont-based Emily Post Institute, which promotes etiquette education.

For instance, a note of appreciation can do much in the workplace, Senning says.

"It makes somebody else feel good. It makes you feel good. So it's a skill that is going to serve your kids so well."

You don't have to be Shakespeare. Two or three sentences will do just fine, Senning says.

"Keep thank-you notes short and sweet. This is not the time to write a long narrative about how life is going, because it will slow you down. You won't do the note. The point is to get the note written and out. Again, it doesn't have to be long. You can say something specific about the gift or event."

Parents shouldn't look at it as giving kids a chore, Senning says. Instead, make it a family activity.

"All of you sit down together at the table and do them," she says. "Or just sit down with them, and you can manage the list or something. So it's like an activity you're doing together, not some punishment. It's much more fun. Listen to some music or have a snack."

Such social graces aren't limited to material gifts, Senning says. Have your child write a thank-you note to the teacher for being a good teacher, she suggests, to the baby-sitter for a fun time, or to relatives for hospitality.

At what age should children start? As soon as they're able to involve themselves on some level or another — whether it's tracing the note with crayons or decorating it with stickers. If the thank-you note is for a gift, you can even have children insert digital pictures of themselves wearing or using the gift.

"But do something so you engage the child in the process of expressing appreciation," Senning says.

McCarter wrote notes for her daughter, Abby, during her infant and toddler years. Now that she's 6, Abby enjoys writing them herself. She has pink and purple stationery with her name on it, decorated with "girly" images of ballerinas, flowers and ladybugs, McCarter says. Her 4-year-old son, Patrick, has thank-you notes adorned with sports memorabilia.