The lesson details an approach to teaching positive and negative numbers which uses number pairs and generates inverses that initially avoid any mention or use of negative signs. The material moves pupils from development of key concepts to the use of more standardized notation for number operations. (MP)

Sections look at: (1) Historical Perspective; (2) Naming the New System; (3) The Metric Units; (4) Measuring Larger and Smaller Amounts; (5) Advantage of Using the Metric System; (6) Metric Symbols; (7) Conversion from Metric to Customary System; (8) General Hints for Helping Children Understand; and (9) Current Status of Metric Conversion. (MP)

It is noted that defining subtraction independently of addition through use of physical objects can help one to illustrate the non-commutativity of this operation. Lack of awareness of the importance of the order of the digits may be a primary cause of errors in compound subtraction. (MP)

The material is designed for pupil practice in: (1) associating numerals with sets of objects and finding sums of two or three numbers; (2) subtracting, one- and two-digit numbers with some regrouping; (3) mental computation using the basic operations; and (4) using combinations of basic operations with whole numbers and decimals. (MP)

This material is the result of 1 year of experimental work during the 1976-77 school year with pupils at the fifth-grade level. Once a week students participated in half-hour, small-group sessions in addition to their regular classroom mathematics period. It is felt that the activities described might be appropriate for additional grade levels. It…