Ecology,

The United States Constitution requires the president submit his nominations for appointment for Senate confirmation.  Members of the Cabinet and independent agencies fulfill the executive role of enforcing the laws passed by Congress. Each supervises its areas of responsibility, collaborates on shared interests and handles complex issues. Real examples are illustrated through the U.S. relationship with Mexico and Canada. 

Water is essential to living. When water is polluted naturally, accidentally or on purpose, it must be treated and restored for consumption and beneficial use. The Chesapeake Bay provides a model of individuals, organizations and government collaborating to clean up water for the common good.