The National Civil Rights Museum is a crash course in civil rights history. Exhibits tell us about slaves in the English colonies and abolitionist John Brown's call for slaves to gain "their liberty in any way they could." We learn about Jim Crow laws, race riots in the early 20th century, the founding of the NAACP, the rise of the Nation of Islam, poll taxes, Freedom Rides, and voter registration drives. We ride on buses and stand in jail cells. At the end, we come to Room 306, where, on the balcony outside, King was shot. Visitors can't go inside the room, but a large window reveals a re-creation of it on the day King was murdered. Remnants of a meal - coffee, milk, and a plate of catfish - are on a stool between the beds. A lamp is on. There are cigarettes in an ashtray.

We stand there, staring into the room, while the recorded voice of Mahalia Jackson sings a heart-wrenching version of "Precious Lord."

I wonder what Sam is thinking. In school, when allowed to read books of his choosing, he invariably selects something having to do with civil rights. The Watsons Go to Birmingham, for example. Or Nightjohn, a book about slavery. Or King biographies. I once asked him why he was so interested in the subject, and his answer was at once unsatisfying and pure.

"I don't know," he said, shrugging, an explanation that could as easily apply to why a person becomes interested in stamp collecting. "I guess I just am."

He had wanted to see some of the places he had read about. So here we were, in Memphis.

Walking to the car, I ask his impressions of the museum.

"Amazing," he says.

"How?"

"I didn't know about the lunchroom sit-ins," he says, "or the deaths of the three civil rights workers in Philadelphia, Mississippi, or that the reason King came to Memphis was to help improve the plight of sanitation workers.