I would recommend the Notgrass course, Exploring Government, as well. We just finished using it for DD18. DD20 used it in her senior year and really did it independently. She thoroughly enjoyed how it covered the Bill of Rights and the various amendments to the Constiution, and she was never much of a fan of history or social studies in general.
My just-graduated DD18 also used the course this year, but we did the course together as she is mildly dyslexic and I read parts of it to her to make it go quicker. (We were trying to finish all of her courses by the end of 2018.) She enjoyed the topics that dealt with issues we still face today such as race, terrorism, and politics in general. Both of my girls found the course engaging, and I was glad that quizzes, tests, and answer keys were included, so there are options for grading the course.