When I taught 8th grade Social Studies, one of the classes I taught was an "Influences on the U.S. Constitution" course in 9-weeks (!right?), that focused on the development of political thought contributing to the framing of the Constitution (think Magna Carta, Locke, Hobbes, Montesquieu, the Mayflower Compact, English Bill of Rights, etc.).
I cobbled together a bunch of resources for my students, relying heavily on (and still heartily recommending you utilize) iCivics free lessons plans and materials.
But it quickly became clear my students needed more than 1 to 2 day lessons and were having troubles linking the political thoughts of the1700s to decisions and the political arena today. They would have benefited from selected readings from Fault Lines greatly.
Where Fault Lines is strongest is in pointing out how conflicts (both in theory and practice) in the past shape and define our political system and decisions now. It's the answer to the "Why do I have to learn this?" question that inevitably comes up when you're asking an 8th grader to read a document from the 1700s. Sure, you can point them to the Constitution, but my students had a hard time reading that and understanding how it shaped their lives, now.
I don't know that I would teach the entire book, but excerpts -- such as "It Takes Two to Tango / Bicameralism" and "Taxation without Representation / The District of Columbia" -- are excellent reads for in-class instruction and discussion, depending on the specific objectives you're teaching.
Other Constitution Resources Links: