Have you ever heard an older person say, "I'm going outside to catch a breath of fresh air?" I doubt that person did the same things we're going to do, but "catch" some air is what we are about to do!

We have some sandwich bags - not the kind with the "zip-lock" tops, and not the kind with the fold-over tops. These are plain, plastic bags. First of all, open your bags, and sniff the inside, so you can know how an empty, unused, plastic bag smells.

Now, holding your bags open, swish them in the air so that they will fill with air. Quickly close the tops, twist them a bit, and put rubber bands on them to seal the air you caught inside the bags.

There are several things we can do with our air bags:

(1) squeeze the trapped air and describe how it feels;

(2) sit on the bag or on several bags at a time to see if the bags can support weight;

[What new thing do we know about air bags supporting weight? Some cars now have air bags that pop out of the steering wheel or dashboard if the car is hit. These air bags prevent the people from being forced into the windshield or the dashboard. By supporting the weight of the people in the car, the air bags can prevent serious injury in accidents. Air bags can injure small children; they should ride in the back seat anyway, and all occupants of the car should use their seat belts.]

(3) look through the bags to see if you can see other people through them;

(4) open the bags a little and smell the air to see if any odor can be detected that is different from the usual smell of the plastic bag;

(5) take the bag outdoors, open it, empty out the air, fill it with outdoor air, bring it back inside, and explain how they can be sure it is filled with outside air and not inside air;

(6) collect samples of air from other places around the school (* e.g., in the basement, closet, hallway) and do all the things with the bag that you did with the classroom air.

(7) collect air samples from the fridge, and place the bags of cold air onto the countertop in the classroom, to see if moisture condenses on the outside of the bags.

* Who knows what "e.g." means? It is the abbreviation for "exempli gratia" (say "ex-EMP-lee GROTT-see-a"), which is a Latin phrase meaning "for example."