This text was written under the auspices of the School Mathematics Study Group (SMSG) as a means for preparing teachers to teach the SMSG text Mathematics for Junior High School, Volume I. Included throughout are comments on suggested methods of presenting material to seventh graders. In this text, class exercises are interspersed throughout, with answers at the conclusion of each chapter. Answers to the exercises at the end of each chapter are found at the end of the book. The text was written with the thought that an instructor would be available, though sufficient details have been presented so that a teacher should be able to master the material independently. The material in the book should help any teacher teach a modern approach to mathematics that deals with: (1) an emphasis on the rationale of the fundamental operations; (2) a discussion of properties and structure of the number system; (3) attention to concepts of non-metric as well as metric geometry; and (4) exploration of other systems of numeration as a device for strengthening the understanding of our own decimal system. (Author/RH)