This text is one of the sequence of textbooks produced for low achievers in the seventh and eighth grades by the School Mathematics Study Group (SMSG). There are eight texts in the sequence, of which this is the sixth. This set of volumes differs from the regular editions of SMSG junior high school texts in that very little reading is required. Concepts and processes are illustrated pictorially, and many exercises are included. Similarity of triangles is the focus of the first chapter (12) in this volume. The use of ratios and scale factors is introduced, and the computation of percentages by construction of parallel lines on a grid is developed. In chapter 13 the emphasis is on computation with rational numbers in both common fraction and decimal forms. In this context exponents are introduced. Chapter 14 deals with motion geometry and perpendicularity. (SD)