Thank your child when he brings you something you requested or after he helps pick up his toys. Make the lesson fun for him by incorporating it into playtime: Toss a ball back and forth and holler "Thank you" each time your child returns it, suggests Kathryn Ecklund, Ph.D., director of psychology at the River Oak Center for Children, in Sacramento, CA. For holidays and family birthdays, encourage him to make presents, such as a drawing or a colorful collage, so he discovers how it feels to be on the receiving end of heartfelt appreciation.
Kids this age only understand why they should say thank you for material objects, like a gift. Doing so for actions or kind words is a complicated notion, so don't ask your child to show appreciation when, say, someone tells him he's clever. And don't expect him to fake joy over gifts he doesn't like. When he unwraps those socks, just thank Grandma in front of him, and maybe he'll chime in.
Help him remember the proper response, but avoid the classic "What do you say?" since that can feel like a test, says Ecklund. Instead, simply state, "I'd like you to say thank you for the cookie," and he'll get the hint without feeling put on the spot.
DON'T FORCE IT
Ask only once or twice, then drop it if your child clams up. "Parents sometimes threaten, 'You better say thank you, or I'm giving it back,' but that's one of the worst things you can do, since you don't want your child to associate blame or shame with being polite," says Shecket. Praise is far more effective: Every time your child says thank you, give him a kiss and a hug.