## Comparing Lengths, Weights, and Capacities: Overview

In this chapter, children are introduced to basic concepts of measurement, including measuring length, capacity, and weight. At this level, children focus on the foundational concept of comparing measurable attributes of objects.

To understand measurement, children need to be able to make general comparisons. Precise measuring is a skill that develops over time. Children begin to make comparisons of length by handling objects or aligning objects to discover which is taller, shorter, or longer. Experiences with lifting objects help them to compare weight, and experiences with filling containers of different sizes with water, sand, or rice will help children compare capacities. It is essential for children to have various experiences with manipulatives for them to gain understanding and skill in measurement. As children gain a sense of relationships from comparison experiences, they will build a foundation to later understand the relationship between arbitrary measures, standard units, and symbolic numbers. These comparison activities also help children develop logical thinking, perceptual skills, and spatial awareness.

Kindergarten children are not expected to measure with standard units. Emphasize language such as shorter, longer, about as much, and about the same. Look for opportunities during the school day to reinforce these concepts by asking questions such as the following.

• Who is taller, Mary or Shana?
• Which glass do you think holds more?
• Whose backpack is lighter? How could we find out?
• Which container holds more?

Most children of Kindergarten age are motivated by the world around them to explore measurement. Prepare a learning center that includes objects of various sizes and weights, containers of various shapes and sizes, and sand or rice for exploring the capacities of the containers. Ask parents to help provide the different objects and containers for you to place in the learning center. While working in the center, have children lift pairs of objects to compare their weights. This will help them to see that larger objects are sometimes lighter than smaller objects. Have them draw pictures to record their findings, labeling them with the words heavier and lighter. Then have children explore the weights of three objects and order them from heaviest to lightest and lightest to heaviest, recording their findings in a similar way. Have children fill pairs of containers with sand or rice to compare their capacities. This will help children understand that the size and shape of containers affects their capacities. Again, have them draw and label pictures to record their findings. Then have them order three containers from least to greatest capacity and then from greatest to least capacity. Have children record and label their findings. You may wish to display children's completed work near the learning center as a reference when doing graphing activities.

Graphing activities are natural extensions from measurement activities because they continue to develop comparison skills and concepts. Help children graph results from measurement activities by coloring boxes to show data using simple bar graphs. You can also have children estimate and graph data by prompting them with questions such as

• How many items on this table are longer than a pencil? shorter than a pencil?
• Which containers on this table hold more than this cup? less than this cup?

Remind children that estimates are reasonable guesses and no estimates are “wrong.” Help them to gain confidence in estimating by providing different activities and praising their efforts. Children will enjoy choosing items to compare.