Understanding Physics follows the trail blazed by Project Physics, but incorporates the most recent advances in understanding how students learn physics and where they encounter difficulties, promotes a more active engagement with the material than its predecessor, and offers more flexibility to instructors in adapting the course to the needs of their students and to their own needs and interests. Thus, for eample, the text is divided into two self-contained semesters which may be studied in either semester and in any order. The course materials comprise The textbook The Student Guide, containing inquiry-based laboratory investigations and additional materials This Instructor Guide, containing examination questions, resource references, and other helpful information