I've found the perfect book for explaining to kids the difference between "need" and "want".  The mom in Almost Zero by Nikki Grimes reacts more strongly than I ever have, but it was effective.  When Dyamonde Daniel demands new hightop red sneakers, her mom hides all of the girl's clothes.   The 3rd-grader is reduced to wearing the same outfit every day and washing it out angrily every night.  What really changes Dyamonde's outlook, though, is when a friend's house burns down.  This classmate really does need new clothes and Dyamonde starts an amazing clothing drive.  This easy chapter book  makes a great point,and it's funny too.