Consistent with NCTM standards, this book employs an investigative approach to elementary mathematics instruction. This philosophy is based on three central tenets: 1) making mathematics relevant to the everyday lives of children 2) making it problem-base or inquiry-based and 3) making it understandable and meaningful. A wealth of probes and investigations in the text and accompanying website provide an understanding of mathematical content, the psychology of mathematical learning, and the latest, research-based teaching methods. In addition to general updating, changes in the new edition include simplifying the format, an increased focus on big (connective) ideas and new material on the design and use of scoring rubrics. New to this edition is an instructor website containing for each chapter: objective questions with answer keys, additional probes and investigations, writing assignments, and video clips illustrating the use of the investigative approach and related probes and investigations.