Last week, David* didn't come to school for two days. He came back with a note from his mom: "David was absent because his asthma was really bad."

Two years ago, I worked with a girl named Diana, who seemed to be in a perpetual fog. I checked her Individu-alized Education Plan, talked with our special ed teacher, and learned that she literally was in a fog: She had lead poisoning and a learning disability, and she had an extremely difficult time understanding, processing, and recalling information.

That same year, two of my students were diabetic and others were overweight and out of shape. They, too, were part of a national trend. (See sidebar.)

But what does this have to do with life in my classroom? Diana has a hard time retaining and processing information. Martin, an outgoing, athletic boy, has to take it easy it in gym class and on the playground because exercise can trigger an asthma episode. Overweight nine-year-old Shayla can't run halfway around the school without stopping to walk. María has to have a special nurse come to school every day to give her insulin and monitor her diet. So what should I do?

Of course, it is my job as a teacher to make sure individual children are cared for and to be sensitive to their medical needs. But asthma, lead poisoning, obesity, and diabetes are more than individual health problems. They are public health problems that plague my city (and all others in the United States) and that disproportionately affect poor people, people of color, and other populations that are concentrated in urban areas.