Grade specific website that has everything from lesson plans to student interactives and mobile acts. They even have professional development tools that every teacher can benefit from.
Founded in 1907, the Organization of American Historians (OAH) is the largest professional society dedicated to the teaching and study of American history. The mission of the organization is to promote excellence in the scholarship, teaching, and presentation of American history, and to encourage wide discussion of historical questions and equitable treatment of all practitioners of history.