In Mexico, more than 60 percent of the land is severely degraded, and soil erosion leaves 100,000 square miles of grazing and cropland unproductive each year.
According to figures from the Natural Heritage Institute in San Francisco, unsustainable farming practices--and increasingly, desertification caused by climate change--drive 900,000 people off the land each year.
Start video when screen reads: "Symptom: Social Scars." (about 16:03 on the counter) This clip is used with both the Popcorn Party and Small World activities.
Stop video after this scene: "Affluenza, the disease of consumerism, is spreading around the world... so it's really critical that we here in North America begin to alter our patterns of consumption and set a better example for the rest of the world of what the good life really is, or none of us are going to have a good life." (about 18:57)
Slice the apple into quarters. Set aside three of the quarters to represent the oceans of the world.
Ask: What fraction do they have left? (one quarter) The quarter of the apple represents the land of the Earth.
Slice the quarter in half. Set aside one half to represent land inhospitable to people: polar areas, deserts, swamps, very high or rocky mountains.
Ask: What fraction is left? (one eighth) The one-eighth of the land represents where people live but not necessarily where the food is grown.
Slice this piece into four sections and set aside three of the four sections. The three sections represent areas too cold, wet, rocky steep or with soil too poor to produce food. The remaining portion contains cities, towns, suburbs, highways, shopping centers, schools, parks, factories, parking lots and other places where people live but do not grow food.
Carefully peel the remaining slice. This represents the soil surface on which humankind depends. It is less than five feet deep--a fixed amount of food-producing land. This fixed land is all that is available for the increasing number of people and other living things that rely on the land for food. The Earth's population is now 5.8 billion people. In the next century that number is expected to rise to 8 to 14 billion people.
Discuss what it means to have finite resources. Compare this small fraction of arable land with the effect that humans have on the Earth as a whole.