HippoCampus Online textbooks organized by time period and a typical school semester. Information is presented in short videos and text. There are AP and general education versions (see menu at left side to choose).
History.comThe History Channel’s website has history categorized by time periods and topics. You will find both articles and videos on history topics. Topic lists are in bottom portion of the page.
ShmoopThis site has the usual time period information as well as special sections on Native Americans, American Fashion, and Women’s Movements.
Library of Congress American Memory CollectionThis is a great one-stop source for primary documents. See the original Declaration of Independence, Constitution, declarations of wars, and much more from various U.S. History time periods. Most of the collection is original documents and artifacts from the daily lives of citizens and immigrants. This is an excellent source for photos.
National Archives National History Day Topics Online is the official website for National History Day 2012 research . Near the bottom of the page, you will find the official Tag for this years theme. This page has links to tons of primary documents that have been tagged as relating to this year's theme.
Factmonster Inventions Pagehas links to an encyclopedia of inventions and other resources, such as inventions by women, black scientists and inventors, and a timeline of inventions.
Lemelson-MIT Interested in creating your own invention? Lemelson-MIT (from MIT college) has resources, programs, and information for upcoming innovators. They also have links to other resources on the web for innovators, both kids and adults.