Have the letters L U C K Y spread out across the Primary room before singing time. Choose a child to pick a letter and put it on the board. Before they sit down have them say something that they feel LUCKY to have. ex: prophet, apostles, family, body, Holy Ghost, Jesus, friends, etc.
After they sit down, sing a song. At the end of singing time, see if they can spell out LUCKY and bear your testimony on what you feel you are LUCKY for :)