I'll be doing those lessons for grades 2-6 from my Computer Lab as well. I plan to use a website called "Ben's First Government for Kids."
http://bensguide.gpo.gov/index.html
My plans aren't complete but I think we will complete an Internet Treasure Hunt with the older students. The little ones will be harder for me simply because I don't have nearly as much experience with that age group.
I saw a news segment last week. A congressman became upset because Americans could not answer simple questions about our Constitution and how it came into existance. Most of what he was talking about I taught in 5th grade Social Studies, but we now have a mandate to teach lessons on the Constitution across the country on or around September 17.