- tributary
- environment
- drainage basin
- natural resources
- region
- irrigation
- erosion
- modify
Also, know the various landform regions of the contiguous United States. They are (from lesson 2): the Coastal Plain, Appalachian Mountains, Piedmont, Interior Plains - (comprised of the Great Plains and Central Plains), the Rocky Mountains, the Great Basin, and the Sierra Nevada.
Remember, the United States is a very large country with a great variety of landforms. These landforms include mountains, hills, plains, valleys, deserts, rivers, and lakes. The United States' climate is also very diverse. From wet, tropical climate regions to arid deserts, and polar tundras, the United States' climate varies because of the many places' distance from the equator as well as those places proximity to large bodies of water.
Here are the slides and answers for pages 48 - 49 in the textbook.