How I Use It
In my history classes, I often use primary sources that I've found on the LOC website to generate discussions, or simply to work on students' ability to think critically and examine items from a historical time period. The Library of Congress has a tremendous catalog of images, letters, and many other types of historic documents, along with lesson plans, collections, and other teacher resources. By approaching the activity as if it's a mystery to be solved, students look/read the document much more carefully than if they are told all of the pertinent information beforehand.
I love the Library of Congress resources. It is especially helpful for teachers who are focused on teaching topics or themes from American history as that is the bulk of their catalog of items (world history items are adding more all of the time, but nowhere near the volume of the U.S. items). It helps to make history come alive for students, which especially for the younger grades, can often be a struggle ("why do we need to learn about what happened to all of those dead people?"). The use of primary sources also helps to remind us as teachers that our job isn't simply to teach our subject matter, but perhaps even more important, to teach the skills that will be successful in any future they decide upon (critical thinking, close examination, asking informed questions, making inferences based on information, etc.).