Grades: 3 - 4
Purpose: To demonstrate that ozone air pollution can cause rubber to deteriorate.
- four identical natural rubber bands
- two metal coat hangers
- plastic bag
- magnifying glass
preparation - 15 minutes
10 minutes observation after one week, two weeks, three weeks, four weeks
Bend each hanger into a rectangle. Slide two rubber bands onto each coat hanger, making sure they are tightly stretched. Hang one coat hanger in a shady place outdoors so that it is out of the sun. Put the other coat hanger in a plastic bag and seal it tightly. keep it indoors in a drawer.
After a week, check the rubber bands hanging outside. Are they cracked and broken? Use the magnifying glass to look at them carefully. Compare the rubber bands kept outside with those kept in the bag. Stretch each band the same distance. Do you notice any difference? You can re-hang and re-store the rubber bands for a few more weeks to determine what happens to them over a longer period of time.
Expected results and the reasons they occur:
The rubber bands on hangers stored indoors should not show deterioration. The rubber bands on hangers kept outdoors will show cracks/breaks and will look deteriorated due to the effects of general weathering (i.e. exposure to weather) which includes exposure to ozone.
Activities adapted from the Puget Sound Air Pollution Control Agency's "Clean Air Express," and from "Where's the Air," Wisconsin Department of Natural Resources.