This is one of a four-volume series intended to improve students' (grade 6-adult) critical thinking through evaluation of conflicting viewpoints of United States history. Each lesson is a self-contained problem that can be integrated at any point in a corresponding history unit. The book represents both analytical and narrative history. Unit One offers a guide to critical thinking with exercises to develop differing types of skills. Unit Two has nine lessons dealing with the New Republic. Unit Three focuses nine lessons on the issue of slavery. Unit Four's nine lessons examine the Civil War. (EH)