Having now seen how the plant and animal life are tied in this reciprocal relationship it makes us aware of the necessity to take care of the earth for future generations and ourselves. As part of our third grade curriculum on communities, we would be studying the rights and responsibilities of the people and the government in helping to prevent possible problems with the ecology of the earth. This, however, is not an easy thing and students need to see that there are two sides to a problem (sometimes more) and that it may not be as easy as they think to change things. In this area, there are many possible projects but for my third grade class I would like them to research one of a group of air pollution sources and gather information about what it is. There are a number of web sites that provide information and are child friendly. Then they will offer two suggestions as to how the problem could be solved.
After they have done this each student will plan out a poster and title illustrating the problem they have chosen (see Lesson Plan #2).
As an addition to this research they will then compose a letter to a local government official stating the problem they are concerned about and requesting that that person do something about it (see Lesson Plan #3).
How does pollution affect plants? How Can We Help?
While we are still able to breathe, there are many days when the pollution levels make it difficult. Chemicals and gases in the air that should not be present cause air pollution. Three main environmental problems that affect plants include: Acid Rain, Global Warming, and Ozone Depletion.
Acid rain begins as normal rain but when it falls through clouds of pollution the rain changes into a weak acid. Water vapor sometimes mixes with the exhaust from cars, and factory smoke stacks as it moves over the land. This combination of nitric oxide and sulfur dioxide dissolves in the clouds. This acid can sometimes be as strong as vinegar (se Appendix A, Experiment #9). 16 This acid is strong enough to damage trees, dissolve marble, and kill fish in ponds and lakes. Small lakes and ponds can be helped temporarily by the addition of baking soda or limestone. The best cure, however, is to control the pollution that is the cause. Acid rain can measure 2.0 or lower on the pH scale.17
Global Warming or the greenhouse affect is connected to the fact that the earth is a closed ecosystem. The temperatures are kept to a certain level so that plant life can thrive. The earth’s temperature is partly the result of the stratosphere that traps gases in the troposphere and stratosphere. Too much heat would make the earth warmer and with hotter temperatures the balance of life would begin to erode. The so-called greenhouse gases – carbon dioxide, water vapor, ozone, methane, nitrous oxide, and chlorofluorocarbons - trap heat that is reflected off the earth’s surface. Nature tries to balance itself, but the things that people do upset it. When people burn wood, coal, and oil, more carbon dioxide is released into the air. The carbon dioxide slows down the movement of heat and acts as an insulator. The result is what would happen if the earth were put inside a closed jar (see Appendix A, Experiment #10). 18 The earth gets increasingly warm from the sun but it cannot cool off. Trees are an important solution to the problem since the trees help to remove carbon out of the air. Saving the rain forests from destruction would help. Some scientists speculate that if the earth’s atmosphere rises a few degrees it could have a devastating affect on the planet. Plant life would be negatively impacted and the polar ice caps would begin to melt. People often confuse the issue of global warming with that of the ozone depletion but they are two separate occurrences though both are major environmental problems.19
The ozone is a thin layer of gas that is about 12 miles up in the earth’s stratosphere. This gas helps to protect the earth by filtering the sunlight that hits the earth. Without that layer higher than normal levels of the sun’s ultraviolet radiation would come down and affect the population. These harmful rays mean more skin cancer, cataracts, and lung problems from increased smog levels. Chemicals like the chlorofluorocarbons in refrigerators and air conditioners harm the ozone layer as they rise into the air. Again people can help if they change their buying habits. Don’t purchase foam products that can damage the ozone when they are burned or put in landfills. Use recyclable paper or plastic cups instead of Styrofoam that is also toxic. Refrigerators and freezers should be kept in good running order and if possible limit use of air conditioning or use a fan instead. Scientists measure Ozone depletion by using satellites. The layer is getting thinner, and over places like Antarctica it is completely gone. 20
As a culminating activity the class would make a hypermedia presentation about the need to take care of the earth using a student PowerPoint program.