Start the game by selecting an object in the room (or car) and give clues to your child so he can try to guess what the object is. Say, “I spy with my little eye, something that is… (give a hint of color, shape, use, etc). Then, have your child ask up to 20 "yes" or "no" questions to see if he can figure out what it is. Then, switch and have your child pick an object while you ask the questions.
This is a wonderful game to play while commuting or during waiting times.