Want kids to eat something healthy? Put a smiley face on it.

A new study finds that labeling healthy foods with smiley face emoticons may be an easy, inexpensive way to get kids to make good cafeteria choices such as fruits, vegetables, plain fat-free milk, and entrees with whole grains.

At an inner-city school in Cincinnati, researchers marked healthy foods with a green smiley face for students from kindergarten through sixth grade. Three months later, they created a "Power Plate" featuring four of these healthy foods. Kids who chose the special plate were rewarded with a little prize: a sticker, temporary tattoo or a mini beach ball. Prizes were also given out by researchers whenever they saw students with four healthy choices on their trays.

The smiles and prizes seemed to pay off.