Investigating Mathematics has been designed as a supplement to regular mathematics classes for the high school students. The aim of this volume is to help anyone wishing to investigate the nature of mathematics as a human activity by forcing us to reflect on our mathematical and intellectual presuppositions and to learn through discussion and exploration. Each unit is divided in three sections that provide: a scaffold for understanding the questions, perspectives, and decisions made in each instance, an original text section that presents ideas as they were originally encountered by mathematicians, and an opportunity for students to sustain their exploration of each topic.