This booklet, one of a series has been developed for the project, A Program for Mathematically Underdeveloped Pupils. A project team, including inservice teachers, is being used to write and develop the materials for this program. The materials developed in this booklet include the idea of reciprocals, and counting fractional parts. Several mathematical problems involving the application of the above principles are included in the sections designed for student activity. Accompanying these booklets will be a "Teaching Strategy Booklet" which will include a description of teacher techniques, methods, suggested sequences, academic games, and suggested visual materials. (RP)