This supplementary modern mathematics textbook is to help in-service teachers to broaden their background in mathematical concepts and ideas for grades 1 through 9. This in-service course was written with two basic objectives: (1) to help teachers to become familiar with some of the newer mathematical ideas and concepts for grades 1 through 9, and (2) to suggest ways in which creative learning can become part of the school program in mathematics. Materials from rectangular coordinates, the arithmetic of signed numbers, the use of variables, and the concept of mathematical function are developed in this text. (RP)