Goal - American citizenship and a thinner population

The average American citizen knows less about our system of government than someone from another country who has become a naturalized citizen. (Made up fact I think is correct.)  I decided that I wanted to learn everything that people studying to take the citizenship test would learn.  I figured it would be good to have goals as well as learning random factoids or tidbits on larger subjects.  I need to find a study guide.

Today I learned about pros and cons for having a fat tax (again, Chuck and Josh and Stuff You Should Know.)  Studies show that having a fat tax would raise food prices across the board.  People who are struggling to get by as it is can't take a 3% increase in all of their food costs, but maybe that's what it will take to get people to stop buying chips and start buying carrots.  I can't really talk because I eat a lot of junk food (and let's not start talking about my soda habit - I have to have some vices.)  I honestly think if they started charging a 60 cent tax on coke, then I might curb my habit.  Anyway, it will probably never happen.  Nanny state arguments and all.  Of course, they did pass taxes on cigarettes so I could be wrong.