In one fourth-grade class at Lafayette Elementary School in Washington, D.C., proper hygiene is part of the lesson plan. With a classroom full of active, physical kids -- at least one of whom always seems to have a cough or sniffle -- it had better be. The classroom can be a Petri dish for germs.
"Whenever we send our children to school, they are going to share whatever germs and infections with the children around them," said Dr. Richard Besser, former head of the Centers for Disease Control and Prevention and a consultant for ABC News. Every little itch, every yawn, every sneeze, every furtive pick of the nose is potentially contagious.
To illustrate just how easy it is for germs -- and viruses such as the H1N1 flu -- to spread, Besser designed a classroom demonstration, caught by news cameras.
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"We're going to be doing an experiment on how germs spread," explained Besser. The key to the experiment was a harmless powder Besser put on the hands of two students, Mae and Martin, functionally "infecting" them. Then the class took part in what the rest of the students thought was an ordinary science lab.
For the lab, Mae and Martin passed around school supplies. Their little hands touched other little hands. Supplies were shared, borrowed and returned. By the end of an hour, everything had been passed around.
And then it was time to explain the real purpose of the exercise.
It turned out that the powder was detectable under a blacklight. When Besser made the room dark and flipped the blacklight on, specks of powder were visible everywhere -- on dozens of hands, noses, mouths.
"What we wanted to see was, if these two were sick and had germs on their hands, how many of you ended up with germs on your hands or your face?" Besser asked.
The answer was simple: everyone.
"Look at all those germs!" the doctor exclaimed.
The kids were clearly intrigued. They piped up when Besser asked what they had learned.
"Germs can spread when you just shake hands," said one student.
"Germs can spread when you touch different places, like they can get in your eye if you rub your eye," said another.
"No matter where you touch your body, you put germs there," said a third.
But were the experiment results -- with every child having "contracted" the germ -- typical, at least in a fourth-grade setting?
"That's typical," said Besser. "If you look at how children play, they're sharing, they're touching, they're touching their face. So germs from one child will go to another child and go to that child's face."
The fact that all the kids got powder on their bodies did not mean that in the case of actual germs, everyone would have gotten sick, however, Besser said.
"Depends on how many germs they picked up, depends on underlying health," he said. "But many of the children would have gotten sick."
Besser said that, unfortunately, there's not a whole lot parents can do to keep their children from getting exposed to germs. But, he added, once a parent knows a child is contagious, it's up to the parents to avoid infecting the whole school.
The take-away message is that germs spread in a classroom. So if your child is sick, don't send them to school.
Many children in the class had a strong understanding of basic hygiene already. Some even had made their own refinements. One student explained handwashing.