This volume is the twenty-second in a series of 29 coordinated MINNEMAST units in mathematics and science for kindergarten and the primary grades. Intended for use by second-grade teachers, this unit guide provides a summary and overview of the unit, a list of materials needed, and descriptions of seven groups of lessons. The purposes and procedures for each activity are discussed. Examples of questions and discussion topics are given, and in several cases ditto masters, stories for reading aloud, and other instructional materials are included in the book. The distinction between counting measure and measure of amount is introduced in the first lesson. Subsequent lessons deal with the use of fractions in the measurement of weight, length, Mag of angles, time and area. In the final section, rules for calculation with fractions are developed. (SD)