EPA's Global Warming Wheel Card is a hand-held tool that you can use to estimate your household's emissions of carbon dioxide and learn how you can reduce them.  One side of the wheel illustrates how much carbon dioxide a household contributes to the atmosphere per year through activities such as driving a car, using energy in the home, and disposing of waste. The other side shows how changes in behavior (such as buying a more fuel-efficient car) can reduce your emissions.  The complete Global Warming Wheel Card Classroom Activity Kit has eight components.