Children naturally make comparisons. At one time or another, many children have stood back to back with a friend to find out who is taller. They have placed their feet next to each other to find out whose foot is longer. They have gone shopping and "matched" their bodies to different sized clothing to find clothes that fit. All these experiences involve comparing, which lays the foundation for matching and, subsequently, learning to measure.

Comparing and measuring are important science skills. When scientists do experiments, they often need to measure; that is, using numbers and standard units of measure, they describe such properties as length, volume, weight, and temperature. Similarly, when students do classroom experiments, they will need to have developed skills in measuring these properties. Even outside the classroom, students have frequent opportunities to measure and compare; for example, when they assemble toy models, fit pieces into jigsaw puzzles, or chart their heights. In fact, comparing and measuring are key ways children make sense of their lives.

Comparing and Measuring, a 16-lesson unit designed for first-graders, gives students a variety of experiences in comparing, matching, and measuring. Throughout the unit, students will observe similarities and differences among objects and match and measure lengths, heights, and distances.

Lesson 1 begins with a class brainstorming session in which students discuss what it means to compare. They begin to recognize that when they identify similarities and differences they are comparing. As a pre-unit assessment lesson, it provides you with a sense of the kinds of comparisons students are making at present and the methods they use to make them.

In the next three lessons, students continue to explore making comparisons. In Lesson 2, they make life-size cutouts of their bodies and use the cutouts to compare their heights. This experience prepares students for matching their heights with adding machine tape in Lesson 3. Students begin to see that when matching the tape to an object, they need to determine both a beginning and an ending point. In Lesson 4, students match the lengths of their arms and legs and record their results on a representational bar graph. When comparing the information on the arm and leg graphs with the information on the height graph from Lesson 3, students begin to recognize the importance of a common starting line.

In the first four lessons, students compare and match lengths either their own size or smaller. In Lesson 5, students are challenged to match larger objects. As they discuss which object might be the largest, students are introduced to the idea of making predictions. In Lesson 6, students begin to discover that matching distance is another facet of matching length. They flip toy Flippers™ and use adding machine tape to represent the distance the Flippers™ have traveled.

In Lesson 7, students make the transition from matching to measuring length by quantifying nonstandard units of measure--in this case, their own feet. Through their measuring activities and a reading selection, students are introduced to the idea that using nonstandard units of measure produces varied results. In Lesson 8, students continue to get varied results as they use different sets of standard objects to measure the same lengths. For example, students who use pencils to measure an object achieve different results from those who use wooden spools to measure it. In addition, students now begin to think about why it is helpful to label their results with the name of the unit they have used to measure. These experiences lay the foundation for Lesson 9, in which the entire class uses the same standard unit to measure. In addition to discovering less variation in their results, students begin to see that using a common standard unit produces results that can be expressed using a common language.

In Lesson 10, students are introduced to a measuring unit that they will use in the next six lessons--Unifix Cubes™. As students connect and stack the cubes, they determine that the cubes are a more versatile tool and that they can be used to measure vertically as well as horizontally. In Lessons 11 and 12, students use larger numbers of cubes to measure larger objects, and gain experience in counting by groups of 10.

In Lesson 13, students make a measuring tool that represents 10 Unifix Cubes™. Students discuss how this tool--a paper measuring strip--eliminates the need for actual Unifix Cubes™. In Lesson 14, students face the challenge of measuring objects that are longer than their measuring strips. Lesson 15 builds on the idea that using an appropriate measuring tool makes it easy to measure long objects. Students create a 100-unit measuring tape and listen to a reading selection to reinforce this concept. In addition, students discover that the measuring tape enables them to measure circumference as well as the length or height of an object.

In the final lesson, students use their measuring tapes to measure how far they can make the Flippers™ travel. Students expand their awareness that measuring is an extension of matching when they compare the methods and results recorded in Lesson 6 with those in this lesson. Lesson 16 also serves as an embedded assessment of the comparing, matching, and measuring skills students have learned during the unit.

Following Lesson 16 is a post-unit assessment that is matched to the pre-unit assessment in Lesson 1. Additional assessments offer students further challenges in comparing, matching, and measuring that will enable you to evaluate students' progress.

After completing this unit, your students will have had the opportunity to develop a basic understanding of key measuring concepts, including using beginning and ending points, using a common starting line, and recognizing the importance of using standard units when measuring. This understanding prepares students for the introduction of formal measuring and the use of units such as centimeters and inches.