Moments of thankfulness open our hearts to joy, fill us with peace, connect us to those around us. They help us feel blessed.

Recently, scientists have been taking a closer look at how positive emotions affect us. Barbara Fredrickson, for example, a psychology professor at the University of Michigan, has found that cultivating gratitude may actually undo the effects of negative emotions such as anger and anxiety.

Too often, though, when we try to teach our children thankfulness we go about it in surprisingly negative ways. We wait until moments when we're worried we have spoiled them for life. "You ought to be grateful for all the stuff you have," we tell them angrily after we have tripped over their toys for the 10th time.

Or we teach thankfulness as "reverse envy." I once heard a particularly grumpy Sunday school teacher lead a class in a prayer that was a classic of the genre. "Thank you, Jesus, for all the things we have," she said dourly, as her class of kindergartners bowed their heads, hands folded. "Because we know that there are so many other children who have no parents and no toys and no clothes and no nice house." The underlying idea here is that we ought to value our possessions because others don't have them--an approach more likely to inspire guilt than gratitude.

The reverse-envy approach was studied by researchers at Southern Methodist University and the University of California at Davis, using three groups of volunteers. One group kept a daily log of five hassles or complaints. The second group wrote down five ways in which they thought they were better off than their peers. And the third group wrote down five things each day for which they were grateful.

After three weeks, those in the group who kept gratitude lists reported having more energy, fewer health problems, and a greater feeling of well-being than those who complained or gloated.

What's the best way to help children experience the heart-expanding effects of gratitude?

Here are some simple ways to help children cultivate gratitude on a daily basis.

Give thanks in prayer. Set aside a regular time for thank-you prayers, before dinner or breakfast, or at bedtime. Give thanks for small things--finding a colorful fall leaf on the driveway, getting over a cold, seeing the dog do a funny thing. Young children are naturally thankful, according to Montessori teacher Sofia Cavalletti. She writes in "The Religious Potential of the Child," "The prayer of children up to the age of seven or eight is almost exclusively prayer of thanksgiving and praise."

Say thank you to your family. Research suggests that people are actually more likely to express their thanks to strangers or acquaintances than to their own family members or peers, according to the National Institute for Healthcare Research. But when parents show appreciation to one another, to their children, and to other people in their lives, children learn to do the same thing. When your child does a household chore--even if it's one of his or her assigned tasks--say thank you. When your partner does something considerate, express your appreciation.

Slow down and smell the roses. Babies and toddlers are fascinated by sights and sounds and smells, from the color red to a ringing bell to cookies in the oven. The older we get, the more oblivious we become to the everyday sensory pleasures of the world we live in. When we pause to enjoy them, we regain the openness that is an essential part of gratitude. Make sure your child doesn't spend so much time with electronic entertainment that he or she misses out on the tactile joys of flowers, plants, crayons, paint, music, and dancing.

Create a year-round thanksgiving spot. This is a home altar of sorts. Find a convenient but safe place--the refrigerator door, a bulletin board, or a small table or shelf. Make this a special spot for things you are thankful for--pictures of people you love, souvenirs and memorabilia, handmade treasures, and, of course, your child's artwork. Invite your child to add his or her own items, and set aside time now and then to admire the objects and pictures together.

Teach your child to write thank-you notes. Even if kids write them on a computer, thank-you notes means more when they specifically mention the gift and say something appreciative about it. Writing thank-you notes to coaches, teachers, baby-sitters, neighbors, clergy, and other caring adults helps a child appreciate all the people who care about him or her (and it's a nice antidote to the complaints most adults hear).

Keep a gratitude journal. One way to help your child develop thankfulness is to cultivate it in yourself. In a notebook, write down three to five things you're thankful for every day. Keep the focus small and specific--give thanks for a child's patience during a long wait, for a pan of brownies that turned out well, for a good joke someone told at lunch. You may wish to share the journal with your child.