Measurement

Finding perimeter is a skill that children need to practice in order to develop proficiency. Becoming familiar with perimeter is important to laying a foundation for children's understanding of geometry.

Materials: square or rectangular objects to measure, such as books, checkerboards, shoe boxes, picture frames, crayon boxes, or pencil boxes, for each child or group of children; linking cubes (enough for each child or group of children to measure the perimeter of the object)

Preparation: none

Prerequisite Skills and Background: Children should know how to measure by using linking cube trains. They should understand how to line up the edges to get an accurate measurement.

• Say: I have items here for each of you to measure. We are going to measure the perimeter of each item.

• Ask: Who can remind us what it means to measure the perimeter of something?
  Children should recall that perimeter is the distance around an object.

• Say: First we are going to guess how many linking cubes it will take to measure the perimeter of each object, and then we'll measure to see how close our guess was to the actual perimeter.

• Say: Here is how we do it. Suppose I am going to measure this book. I will first look at it, and then I will look at my linking cubes. I will estimate how many cubes will be on each side, and then I will record that estimate. Next, I will use my linking cubes to measure the perimeter of the book. Then I will compare my estimate with my actual measurement.

• Say: Let's try this together with an object. Everyone choose something you want to measure. (Allow children to choose an object to measure.) Now, look at your object and estimate how many linking cubes will be needed for the perimeter. Write this estimate on your piece of paper. Now use your cubes to measure the perimeter of the object.

• Ask: How did you do? Was your estimate at all close to your actual measurement?
  Allow children to tell about their estimates and measurements.

  Repeat this activity, allowing children to measure as many objects as they have time for and to share their results.

Wrap-Up and Assessment Hints
Measurement provides children with helpful hands-on experiences with geometric figures like those they encountered in Chapter 7. It can help them to develop their sense of spatial relationships, which is fundamental to their understanding of geometry. As you provide opportunities for measuring the perimeter of objects, you can assess how well the students understand the measuring process. Do they understand the concept of perimeter? Do they line up the clips correctly? Do they understand the need for precise measurement? For children who have difficulty, provide objects that are smaller and more easily measured, or pair such children with classmates who have mastered the skill.