classroom.jpgUnit 10 reviews and builds on children's understanding of the measurement of inches and centimeters as measurements of length. Previously, children took measurements from drawings of rulers with objects placed next to them. In this unit, children take active charge of the measuring process and position the rulers themselves. Additional activities have children use measurement to distinguish squares from other rectangles and record measurements in tables.

The study of measurement is important in the mathematics curriculum from prekindergarten through high school because of the practicality and pervasiveness of measurement in so many aspects of everyday life. The study of measurement also offers an opportunity for learning and applying other mathematics, including number operations. It also highlights connections within mathematics and between mathematics and areas outside mathematics, such as social studies, science, art, and physical education.

Nonstandard Units of Length
Students begin Unit 10 by taking measurements with multiple strips of paper and with toothpicks. Lining up these physical units helps children understand the concept of measurement and the arbitrary nature of measurement units. The approach also allows children to see that measurements are inclusive--that a quantity of 5 toothpicks includes 4, 5, 2, and 1.

Standard Units of Length
Children quickly move from toothpicks to inches, and later to centimeters. They take measurements, and they begin to develop a mental image of these standard units. One way to reach this goal is to have children practice estimating length in inches or centimeters.

Rounding to the Nearest Unit
Children usually comprehend rounding more easily when it is associated with the visual reinforcement of a ruler. They can see that a partial unit is either closer to the next whole number or to the previous number. For this reason, rounding is introduced with measuring in Unit 10.
Example: This pencil is 2 toothpicks long and more than half another toothpick. The pencil is about 3 toothpicks long.

Fuson, Karen, Math Expressions, Unit 10 Overview