When he's in the classroom, pediatrician Charles Cappetta of Dartmouth-Hitchcock Nashua goes by "Dr. Chuck." He's been teaching fourth-graders about their bodies for more than a decade, and his program, Granite State FitKids, was highlighted in a 2006 World Health Organization publication about the best programs in the world for promoting physical activity.

How did Granite State FitKids get its start? I started it back in 1997 teaching kids about their bodies and how to take care of them. It started with three schools in the Greater Nashua area and now serves 40 schools throughout New Hampshire and down into Massachusetts.

Why teach fourth-graders about anatomy? This is their body, the only body they're getting. You can't go to Walmart and get a new one. It's empowering these guys, 9- and 10-year-olds, to say, "I don't have to wait."

How do you keep the kids interested? If I was just droning on like a college professor they'd be sitting there snoring their brains out. We're building things on the floors, models of lungs, playing games where we're red blood cells picking up oxygen.

How did you pick fourth grade? In third grade this was too much information too fast. In fifth grade they're like hardened criminals. They've been there, done that. They know everything and they don't laugh at my bad jokes. In fourth grade they're like sponges.

Which Concord schools do you go to? We have been in Concord for three years, first at Conant and Beaver Meadow and now at Kimball. Kimball will finish its last of seven weeks on Monday.