This book examines the study of geometry in the middle grades as a pivotal point in the mathematical learning of students and emphasises the geometric thinking that can develop in grades 6-8 as a result of hands-on exploration. An essay on the accompanying CD-ROM describes the van Hiele framework and how it can help improve teaching strategies and assessment. The supplemental CD-ROM also features interactive electronic activities, master copies of activity pages for students and additional readings for teachers.