PHILADELPHIA—I thought my son would be much older before I had to tell him about the Black Male Code. He's only 12, still sleeping with stuffed animals, still afraid of the dark. But after the Trayvon Martin tragedy, I needed to explain to my child that soon people might be afraid of him.

We were in the car on the way to school when a story about Martin came on the radio. "The guy who killed him should get arrested. The dead guy was unarmed!" my son said after hearing that neighborhood watch captain George Zimmerman had claimed self-defense in the shooting in Sanford, Fla.

We listened to the rest of the story, describing how Zimmerman had spotted Martin, who was 17, walking home from the store on a rainy night, the hood of his sweatshirt pulled over his head. When it was over, I turned off the radio and told my son about the rules he needs to follow to avoid becoming another Trayvon Martin -- a black male who Zimmerman assumed was "suspicious" and "up to no good."

As I explained it, the Code goes like this:

Always pay close attention to your surroundings, son, especially if you are in an affluent neighborhood where black folks are few. Understand that even though you are not a criminal, some people might assume you are, especially if you are wearing certain clothes.

Never argue with police, but protect your dignity and take pride in humility. When confronted by someone with a badge or a gun, do not flee, fight, or put your hands anywhere other than up.

Please don't assume, son, that all white people view you as a threat. America is better than that. Suspicion and bitterness can imprison you. But as a black male, you must go above and beyond to show strangers what type of person you really are.

I was far from alone in laying out these instructions. Across the country this week, parents were talking to their children, especially their black sons, about the Code. It's a talk the black community has passed down for generations, an evolving oral tradition from the days when an errant remark could easily cost black people their job, their freedom, or sometimes their life.

After Trayvon Martin was killed, Al Dotson Jr., a lawyer in Miami and chairman of the 100 Black Men of America organization, told his 14-year-old son that he should always be aware of his surroundings, and of the fact that people might view him differently "because he's blessed to be an African-American."

"It requires a sixth sense that not everyone needs to have," Dotson said.