Texas Law-Related Education has a wonderful website filled with engaging online games, videos, and curriculum. The website is funded and sponsored by the Hatton W. Sumners Foundation and the State Bar of Texas. 

Check out a few of there programs:

Liam Learns...7 Principles of the Constitution - www.texaslre.org/liam-learns/

             Short videos and lessons to help teach the 7 Principles of the Constitution

Oyez, Oyez, Oh Yay!: Civic Resources - www.texasbar.com/civics/index.html

            Videos and lessons to help teach Supreme Court cases