Air is all around, but how often do you think of it? Maybe when it's cold or windy or something smells, but not as often as you inhale it (about 20,000 times a day)!

A Recipe for Air

Even though you can't see air, it is made up of trillions of microscopic molecules. Air is made up of mostly nitrogen and oxygen gases, but there are tiny bits of other gases, as well as particles like dust and ash, water droplets, and sometimes ice crystals. Make your students into air molecules to demonstrate visually what air is and what it does. You'll need five different colors of construction paper cut into strips that can be used as arm bands. Assign one color for each component of the air (nitrogen, oxygen, water vapor, other gases, pollution). Next, assign students to represent the different components of air in the same ratio as real life. In a class of thirty students, twenty-one students will be nitrogen (78 percent), five will be oxygen (21 percent), two will be water vapor (variable), one will be other gases (1 percent), and one will be pollution (variable).

Separate the children according to the color of their arm bands. Talk about the different components of air — what there's more of and what there's less of. Can you see these molecules of air? Which ones do people breathe? People inhale oxygen, but they also inhale pollution.

Are air molecules separated in the air like the students are standing in the classroom? No. Have the children walk around the room and randomly mix themselves up. This is what air is really like, but is the recipe always the same? What about the air right next to a busy highway? The air in a forest? The air above a factory smokestack? It's ideal if you have pictures to show and compare.

Air pollution is always on the move. Remember how China struggled with air pollution before the 2008 Summer Olympics? Their air pollution blows all the way across the ocean and ends up adding to air pollution in the United States. Likewise, air pollution from coal-burning power plants in the United States blows up to Canada and all over the world.

On a smaller scale, if trash is burned in someone's backyard, it can easily move to the neighbor's yard. Have you ever been able to smell when your neighbor has a fire in their fireplace or when they're doing their laundry? That's because smells, scents, chemicals, smoke, and pollution are always blowing in the wind.

In and Out

The air inside and the air outside are actually very different. Think about how people use heaters and air conditioners to control the temperature inside a building. In order to do this, they have to make buildings that keep the warm air inside in the winter and the cool air inside in the summer. They have to be sealed up tight. In most buildings and even in homes, you can tell that the indoor air is different from the outdoor air because it smells different.

Ask your students to take a walking tour around their homes and yards and make a list of the scents they smell. Where are the smells stronger? Ask them to decide if the smells are good or bad. What does it smell like outside on the lawn? What does it smell like in the parking lot or driveway? How about the garage? What does it smell like in the bathrooms? Which air is “fresh” air and which might have pollutants in it? In the driveway you might smell exhaust from cars or lawnmowers, which are major outdoor air pollutants. In the bathroom you might smell cleansers, which are major indoor air pollutants (they're usually made of toxic chemicals).

When your students return to the classroom, have them read out loud some of the smells they discovered. List the items that might be bad to breathe and discuss ways to make your home healthier. Order We're Not Asking for the Moon … Just a Healthy Home and Earth from Kids for Saving Earth (www.kidsforsavingearth.org and click on KSE “Green Shop”) for your library and ask the kids to take it home to read with their parents.