I thought this video might be helpful to show students more about using search engines and how to best utilize them to get information. When looking for primary or government docuements, I thought this video could be a starting point for students to start their research. It's very simple explanation for students.
I really liked the teacher resources on this site. It was applicable for any grade, and was broken up into how much time you would like to spend. There are also a variety of multimedia resources. This was and interesting series as it looks at what scientists and engineers do outside the lab, and how it can relate back to their work. There are also a wide variety of careers and ages of individuals interviewed.
This site gives an explanation of primary resources along with many reputable links to websites that have primary documents. Additional information about using subject directories and search engines will make searching for primary documents a little easier.
This website is a database devoted to historical spoken-word materials. The search engine is still underdevelopment but there is a "galleries" link to find resources. This is an amazing site for students to explore and hear the actual words spoken by historical figures they read about in textbooks. Historical Voice is supported by the National Science Foundation and the National Endowment for the Humanities.