Begin by discussing the main question posed at the beginning of the section. “How do species become extinct and what can humans do to prevent this loss of biodiversity?” Students learned about the rapid rate of loss of biological diversity in the previous section. Now they can connect specific human actions such as farming to species extinction.
Discuss the difference between ultimate and proximate causes of extinction. Emphasize that rarely are human activities the proximate causes of a species becoming extinct, but they are often the ultimate cause due to development, agriculture, or pollution.
Assign What Do You Think? on page 79 so students can write about DDT. Encourage them to think about the international controversies that often accompany environmental issues.
Activity 12-1: Design a Nature Reserve can be used as an open-ended culminating activity and assessment tool for this section or for the entire Ecology unit. The activity asks students to draw on most of the major concepts from the unit and apply them to a particular endangered species.
What Do You Think?
The federal government banned the use of DDT in the U.S. But the government did not ban its manufacture or exportation. Several U.S. companies still make and sell DDT to farmers in other countries. Should the U.S. ban the manufacture and sale of DDT to people in other countries or should those people have the right to buy DDT if it helps them grow food?
When a species such as the brown pelican becomes endangered, how much money, time, and effort do you think humans should spend trying to save it from extinction? Do you feel it is as important for governments to spend money on endangered species as on health care, the homeless, education, weapons, roads, and transportation? Explain why or why not.
Students create a nature refuge in their backyard. You may want to have the class work together to create a nature refuge near the school.