Note: If previous measurement lessons haven’t already taken place, discuss length and width for various items so all students have the same basic understanding of these terms.
“Today we are going to work on measuring lengths of items in our classroom. We will use a variety of different objects to help us measure the length. What might we use?” Accept all reasonable answers. “Let’s start with using large paper clips to measure the length of this book. Before we actually measure, let’s estimate or guess how many paper clips it will take. How many large paper clips do you think it will take?” Write the estimates on the board using a designated color. “Now that we have our guesses, or estimates, let’s measure to find out how many paper clips it will take.” Lay out paper clips end to end to measure the book. Discuss with students why it is important to ensure that each new paper clip is placed exactly at the end of the previous one, without leaving gaps or making overlaps. Record on the board the actual number of paper clips using a different color than the estimate. “Was our estimate close to our actual measurement?” If the estimate was not close, discuss with students their ideas for making a better estimate.
“Now let’s take a look at a way that can help you make a closer estimate.” Connect a row of 10 connecting cubes. “I have a row of 10 cubes, and we will use them to measure the length of my desk. I ran a piece of masking tape along the edge to help keep a straight line. How many cubes long do you think the desk will be? Look at this row of 10 to help you.” Write the estimates on the board. “Let’s see how close our estimate was.” Lay rods of 10 cubes along the masking tape to determine the actual number of cubes. “How close was our estimate this time? Why is it important to make an estimate before you measure?” (Most of real-life math involves mental computations and estimations. In order to examine their own answers for reasonableness, students must have some experience with estimation. Practicing estimation helps to improve mental math skills and computational fluency, and it helps students develop a stronger number sense.) Explain to students that their estimates are never wrong; they are just a guess. Emphasize, however, the concept of reasonableness when making estimates.
“Now you will do a similar activity, but you will be working in small groups. Each group will estimate and then measure several different objects. Be sure to keep track of your estimates and actual measurements using the different colors we’ve chosen for each.” Distribute to each group the Measurement Worksheet (M-1-5-2_Measurement Worksheet.doc) and small paper clips. Have students estimate the length of each object on the worksheet and then measure the length of the object using a small paper clip as a nonstandard unit. Make sure students record their estimates and measurements on their worksheets. Check students’ procedures to ensure that they are estimating before measuring.
Once students have finished the worksheet, bring the class back together. Discuss the answers with students. While their estimates may be different, their actual answers should be very close or the same. “How would your answers change if you used a larger paper clip?” Students should respond that they would need fewer paper clips. Demonstrate so all students can see that larger paper clips require fewer in total. “How would your answer change if you used a smaller paper clip?” Discuss that using a smaller paper clip would necessitate more paper clips.
Once you have finished discussing the results, students can go back to their seats and complete the Lesson 2 Assessment (M-1-5-2_Lesson 2 Assessment.doc). The assessment contains two pictures for which students need to first estimate and then measure the length using nonstandard units such as paper clips, pennies, or cubes.
Extension:
- Routine: Have students find a classroom object that is a certain number of cubes long. In this activity, students learn to estimate a length before choosing an object and then verify their estimates by placing cubes next to the object.
- Small Group: Have students estimate and measure object lengths using connecting cubes. The cubes are interlocking, so the concept of having the nonstandard units touch end to end can be reinforced.
- Expansion: Ask students, “How can we measure the distance around something?” Show students a circular shape such as a large can or oatmeal container. Ask a student to use cubes to measure the distance around the object. Students should see that this cannot be done accurately. Ask students: “Is there a better way we could measure around the object?” Have students try the suggestions offered. A possible suggestion could be to use a piece of string to measure around the object and then use cubes to measure the string. Have groups of students measure distances around different classroom objects by using string.