Free play is so important to social, emotional and intellectual development because it allows children to learn from other children. Yard sports often include a mix of ages of kids who create the ground rules with no adults present, and they put their heads together to solve problems. This environment teaches five lessons missing in formal sports.

Lesson 1: To keep playing, you must keep everyone happy. The most fundamental freedom in all true play is the freedom to quit. Every player has to, in some sense, get into the other players' minds and figure out what they need and want. If you are a big strong pitcher, and a little kid is up at bat, you pitch softly. Everyone's needs are in constant balance. Seeing things from the other person's perspective is how you learn empathy.

Lesson 2: Rules are modifiable and player-generated. For instance, the strongest batter might have to hit one-handed. In some sense, players are learning and practicing the principles of democracy.

Lesson 3: Conflicts are settled by argument, negotiation and compromise. Players act as umpires. They decide whether a hit is fair or foul, whether a runner is safe or out, and whether the pitcher is or isn't being mean to little Johnny.

Lesson 4: There is no real difference between your team and the opposing team. Billy may have been on the "enemy" team yesterday, but today he is on your team. Teams may even change composition as the game goes along. This strong sense of equal ground avoids promoting one sad aspect of human nature: chauvinism.

Lesson 5: Playing well and having fun really are more important than winning. In organized sports, with spectators watching, with a trophy on the line, one has to wonder how many of the players secretly think that Vince Lombardi had it right.

In real life, you must improvise. How you play the game, how much fun you have along the way, and how much joy you give to others are what matters. These skills are taught by informal play.

Organized sports don’t do this. As leagues become more selective every year, kids drop out, becoming couch potatoes who watch sports instead of playing for fun. With informal sports, you can continue your whole life as long as you can find a group to play with.