• Supervise students’ responses to questioning during the length and mass investigations to determine who might need additional practice.
• Read through students’ responses on the I Spy scavenger hunt recording sheet, and use questioning to assess student level of mastery.

“In today’s lesson we are going to further explore measurement and how to make estimates with measurement. Remember that when we estimate, we do not randomly pick a number. That would be more like guessing. Estimating is using information we know to come up with an answer. Sometimes we use benchmarks to help us. Benchmarks are common measurements that can be used as a reference to estimate measurements in length, weight, temperature, time, and area. If I told you a dollar bill is about 6 inches long, could you use that as a benchmark to determine the length of an object? If I told you I am about
5 feet tall can you estimate how tall the doorway is? If I told you a sheet of paper has an area of about 90 square inches can you estimate the area of the top of a desk?”

Review the measuring skills practiced in Lesson 1. Give each student a sheet of white paper and be sure each student has a ruler. Ask students to draw a 6-inch line on their paper. “The line you just drew can be considered a benchmark. It is approximately the same length as a dollar bill. Visualize how long 6 inches is, and then look around the room and find two objects that appear to have a length shorter than 6 inches and two objects that would have a length longer than 6 inches.” Give students some time to think-pair-share with the classmates around them. Ask for student responses and record on chart paper. Discuss what strategies students used when identifying objects. Ask questions similar to those listed below.

• Explain how you knew if an object would be shorter than 6 inches in length. (if it looked shorter than my benchmark)
• Explain how you knew if an object would be longer than 6 inches in length. (if it looked longer than my benchmark)
• Is there any object on our list that you think would be approximately 12 inches in length? What are you basing your decision on?

Confirm some of students’ estimated predictions by having volunteer students measure. Discuss findings.

“Look at this meter stick. It is a little longer than a yard. About how many meters is the height of our classroom doorway? How can using this meter stick as a benchmark help us to estimate?” Give students some time to think-pair-share. Then ask students to share their predictions and thoughts. “What is the length, to the nearest meter, of our classroom? How can using this visual benchmark for a meter help you? Does knowing the height of our classroom doorway help refine your estimate?” Have students share their estimates and ideas. Then have several students measure the length of the classroom and share the measurement with the class. Ask students to generate as many varied answers as they can to complete the following stem: Some objects in our school that are longer than 1 meter are  . . .

Give students approximately one minute to complete the task. Have students share with a partner, and then have each student try to share one object.

Share the Measurement Conversions for Length chart with students (M-4-1-3_Measurement Conversions.doc). Explain to students that this chart shows measurement conversions that can be helpful in estimating length. Pose questions to students similar to those listed below to have them estimate length. To make this more of a kinesthetic activity, designate different parts of the classroom with different units of measurement for length. Ask students to go to that part of the classroom. Discuss results and explain thinking.

• To measure the length of a humpback whale, should you use miles, feet, inches? (feet)
• To measure the length of a couch, should you use centimeters, meters, miles? (meters)
• To measure the length of a shoelace, should you use inches, feet, yards? (inches)
• Is the width of a doorway approximately 1 yard, 2 yards, or 3 yards? (1 yard)
• Is the length of a photo 6 centimeters, 6 inches, or 6 feet? (6 inches)
• Is the height of your desk 1 foot, 2 feet, or 3 feet? (2 feet)

“We also can use benchmarks when we want to estimate how much an object weighs.” Give each student a copy of the Measurement Conversions for Mass chart (M-4-1-3_Measurement Conversions.doc). The goal is not to have students memorize the conversions, but rather to begin to develop a stronger number sense when it comes to various units of measure. To help students get a better sense of the mass of objects, have several objects available for students to hold or visualize along with their corresponding mass in various units. Ask students to look over the chart and make some observations and/or comparisons about mass. Also encourage students to refer to any personal benchmarks they may have related to mass. One example might be how much their dog weighs or how much a bag of potatoes weighs. Record student observations on chart paper.

Ask students to take out a textbook and feel how heavy it is. Explain to students that, on average, textbooks weigh between 1 to 2 kilograms. Show students a paperclip and explain that the mass of a paperclip is approximately 1 gram. Explain to students that, on average, an apple weighs
4 ounces. Ask students to look around the room and find two objects that they think have about the same mass. If possible have a scale available to measure the mass of each object, or students can ask another student to hold the two objects and determine if they have similar masses. Ask students to look around the room and find two objects that have very different masses. If possible have a scale available to measure the mass of each object, or students can ask another student to hold the two objects and determine if they have differing masses.

Pose questions similar to those listed below to have students estimate mass. To make this more of a kinesthetic activity, designate different parts of the classroom with different units of measurement for mass. Have students go to that part of the classroom. Discuss results and explain thinking.

• Would you weigh your bicycle in ounces, pounds, or tons? (pounds)
• Would you weigh a fourth grader in grams or kilograms? (kilograms)
• Would you weigh an airplane in ounces, pounds, or tons? (tons)
• Would a slice of white bread weigh 1 ounce, 10 ounces, or 1 pound? (1 ounce)
• Does an average-sized basketball weigh approximately 2 ounces, 22 ounces, or 22 pounds? (22 ounces)
• Does a chicken egg weigh approximately 6 grams, 60 grams, or 6 pounds? (60 grams)
• Does an adult whale shark would weigh approximately 20 pounds, 200 pounds, or
  20 tons? (20 tons)

“Estimating the mass of an object takes practice. Using benchmarks can help you create a point of reference to make more accurate estimations.”

“Let’s go on a scavenger hunt looking for objects for which we can estimate length or mass.” Pick a location or place students can explore such as the library or possibly outdoors. If this is not an option, students can imagine a grocery store or a home improvement store. (Using sales fliers for these stores is another option because the visual prompt might help students more readily understand which objects to choose.) “Remember to keep benchmarks in mind. If you need to refer to the Measurement Conversions for Length or Mass charts, please bring those along with you.”

Hand out copies to students of the I Spy Sheet (M-4-1-3_I Spy Sheet and KEY.doc). The goal of this activity is not necessarily to finish the entire chart. Rather, the goal is to play with measurement in a creative manner and to look at surroundings to create benchmarks for measurement. While students are working on completing their charts, ask questions similar to those listed below.

• Explain how benchmarks help you estimate measurement. (They give us a visual reference.)
• What is one benchmark you use to help you estimate length? (ruler, meter stick, etc.)
• What is one benchmark you use to help you estimate mass? (textbook, hand weight, etc.)
• When would it be helpful to be able to estimate measurement? Why? (It is helpful to estimate measurement when we have a solid benchmark to use, and we don’t need to be exact. We might estimate because it is quicker, or when we don’t have the proper tools to measure exactly.)
• When is it appropriate to have an estimated measurement? (when we only need to know about how many instead of exactly how many, e.g., when determining clothes sizes, lengths of fabric, number of rolls of tape needed, etc.)
• When is it necessary to have an actual measurement? Why? (when we need to know exactly how many for proper fit or safety reasons, e.g., when following recipes, during building construction, when using money, etc.)
• What unit of measure do you think is the hardest for you to find an example of?
• What unit of measure can you find many examples of?
• What object can you locate that would have a length that measures more than 1 meter?
• What object can you locate that would weigh less than 10 pounds?

Utilize the responses given during the previous part of the lesson to help gauge student understanding. Have students complete the following journal response.

• How does using benchmarks help you make reasonable estimates for measurements of length and mass? Explain your thinking using a few specific benchmarks.

“In today’s lesson we focused on estimating measurements. When we estimate measurements, we want to make sure our estimates are reasonable. Sometimes we might need an actual measurement like when measuring to buy a new sink to replace an old one. Other times we can use an estimated measurement, like when determining how many miles a road trip will be.”

Extension:

Use the following strategies and activities to meet the needs of your students during the lesson and throughout the year.

• Routine: Show students an object or a picture of an object. Tell students what attribute you want them to estimate. Then give students two or three choices for an estimated measure. In their math journal have them record the object, the estimated measurement, and a quick explanation of their thinking. Hand out copies of the Routine Example worksheet (M-4-1-3_Routine Example.doc). The more practice and experience students have with estimating measurement using different units of measure, the more proficient they will become.
• Small Group/Technology Connection:
  • Option 1: In their math journals have students create a chart for length and mass similar to those that follow. As a group, list as many varied items/objects as possible that can be measured using the units of measure in the chart. Share with students the items in the chart to help create a visual benchmark for them for each unit of measure. Using the items listed in the charts, create scenarios for students to consider and answer similar to the ones listed below.
    • Is a dog more or less than 2 kilograms in weight? (usually more)
    • Is a backpack more or less than 10 pounds in weight? (answers will vary)
    • Is the chalkboard more or less than a yard in length? (answers will vary)
    • Is the length of the school building more or less than a mile? (less)

• Option 2: Students who may need additional support with mass might find the following Web site helpful: http://www.studyzone.org/testprep/math4/d/massgram4p.cfm. The site asks students to order objects from least to greatest mass and identify objects that they can measure in grams. Immediate feedback is provided. To review estimating length, the following link has a PDF worksheet students can complete in small groups: http://www.education.com/files/55101_55200/55172/file_55172.pdf. Have students share their explanations and what benchmarks they used to help them. To practice estimating and measuring with a ruler to the nearest  inch or to the nearest centimeter, students can complete the Estimating and Measuring worksheet (M-4-1-3_Estimating and Measuring Length.doc).
• Expansion/Technology Connection: Students who show proficiency in understanding the concepts of length and mass may be challenged by exploring the concept of capacity. Explain to students that capacity refers to the amount a container can hold. As an introduction to capacity, students can use the Web site, Cyberchase: Can You Fill It? http://pbskids.org/cyberchase/find-it/measurement/. Students can estimate how many pots are needed to fill a given container. Then students can check their predictions by completing the task. This activity will help students develop a stronger visual spatial sense of capacity. Students can create a model of the Gallon Man to help understand the relationship between cups, pints, quarts, and gallons. If possible, have various units of measure for capacity (measuring cup, bottle of water, empty 2-liter soda bottle, empty
  1-gallon milk carton) available for students to look at to help solidify the connection between a unit of measure and an amount. Students can explore the relationship between the different units and complete the Capacity worksheet (M-4-1-3_Capacity and KEY.doc) to estimate the approximate capacity of the given objects.

This lesson is intended to give students practice using estimation skills when measuring. Students will understand the difference between guessing and estimating. Estimating is using information you know and not randomly guessing. By using benchmarks students can make more reasonable estimates. Students will be introduced to various units of length in both U.S. and metric units (inch, foot, yard, mile, centimeter, meter) and various units of mass in both U.S. and metric units (ounce, pound, gram, kilogram). Conversions will be shown to students not to memorize but rather to begin to develop a sense of mass in order to make more reasonable and accurate estimations. Everyday objects and/or pictures will be used when students make estimates of measure.