Help your students or yourself learn more about Idaho’s geology at Visit Idaho.
National Geographic has a great site about rivers that you should visit.
This site is a huge help in defining vocabulary and learning all you need to know to teach rivers.
Howstuffworks is another great place to learn about river systems.
This site has some great animation to provide explanation of river landforms, deposition, and river systems. Good demonstration for your lessons.
Great Activities to teach about the water cycle.
Lessons on weathering and erosion.