This is one of the true supersites for education. Take the time to learn how to use this site, you will be very impressed.
http://www.sciencenetlinks.com/ Providing a wealth of lessons, tools, and resources for K-12 science educators, Science NetLinks is your guide to meaningful standards-based Internet experiences for students.
National Geographic is a huge website! It would take a person a long time to go through the whole thing. Take the time to teach your student how to use this website. It is well worth your time, especially for the photographs. For instance, search on volcanoes. This is a wonderful website for for unit studies and research projects.