## Measuring and Comparing Length, Weight, and Capacity: Overview

In this section, children are introduced to basic concepts of measurement, including measuring length, weight, and capacity. Measuring precisely is a skill that develops over time and is learned in progressive steps. In learning to measure each attribute, children will move from comparing objects to determine which is longer or shorter, which is heavier or lighter, or which holds more or less, to measuring objects according to standard units of measure.

The section begins with measuring length. Through direct comparison of various objects and pictures, children will learn to determine which is *taller, shorter,* or *longer* and which is the *tallest, shortest,* and *longest.*

Next, children will measure objects using nonstandard units, such as connecting cubes, paper clips, pencils, erasers, crayons, hands, feet, and shoes. Children need to understand the idea of measuring in tangible units before they can move on to using rulers and standard units. Measuring how many paper clips or crayons long an object is builds a foundation for understanding the relationship between quantities and symbolic numbers. Nonstandard units also make children aware of the need for standard units of measurement. As they measure the same object with units such as their hands or feet, children will see that different-sized units, such as hands and feet, yield different measurements.

Once children have had a variety of experiences with nonstandard units, you can introduce inch and centimeter rulers as tools for measuring with standard units. This is the first time that children are learning to use rulers. You will need to focus on the proper way to use a ruler, emphasizing how to align the left end of the ruler with the end of the item to be measured, and explaining how to determine which number is the measurement. At this level, children will measure to the nearest inch or centimeter only.

Weight in pounds and mass in kilograms are introduced in this section as well. Again, children will begin by making direct comparisons of different objects to determine which is *heavier* and which is *lighter.* Next, children will learn the concepts of pounds and kilograms. At this point they will not find exact measurements in pounds or kilograms. Instead, they will simply compare items to a 1-pound weight or a 1-kilogram mass to determine if they are more or less. Having several items in your classroom that are more or less than a pound or a kilogram will help children to become familiar with these units of measure.

Capacity is the last measurement attribute that is discussed in this section. *Capacity* is the quantity that a container can hold. As with length and weight, children will begin by directly comparing the capacity of containers. To do this they will use a variety of materials such as sand, birdseed, counters, and cubes. Next, they will be introduced to the units of cups, pints, and quarts and will learn that there are 2 cups in a pint, 2 pints in a quart, and 4 cups in a quart. Although some children may be able to determine equivalencies numerically, many may need hands-on experience measuring the number of smaller units that fit into larger units. Finally, children will compare the capacities of various containers to a 1-liter container to determine whether these containers can hold more or less than 1 liter.

To wrap up the section, children will solve measurement problems in which they will be asked both to perform numerical calculations and to decide which measurement tool is needed for a given task.