We did not completely understand the concept of piñatas in Mexico.  After a few birthday parties for the kids and a couple other celebrations we have a better grasp on this tradition.  There is a song sung while the child swings at the piñata and they have until the song is over for their turn.  The person in charge of the piñata can make the swinging process as easy or as difficult as they desire, making it a bit more challenging for the older/stronger kids.  The BEST PART is when the candy starts coming.  Looks like a fumble at a football game!  Everyone just dives in.  Amazing there are not more injuries.  Certainly lots of fun for the kids!