E-book versions of the We the People: The Citizen & the Constitution are now available for all grade levels (elementary, middle school, high school). Thanks to a PTA grant I won, I use a class set of 30 with my 7th graders. The teacher's edition, which comes with the class set, can be purchased separately.
Here's the link for the middle school edition:
Below is a preview:We the People Middle School Textbook