Students will comprehend measurement systems, procedures, units, and measurable characteristics of objects. They will utilize the proper methods, instruments, and equations to ascertain measurements and apply addition and subtraction to resolve word problems involving length. Students are going to:
- acknowledge the characteristics of length.
- compare items based on these characteristics.
- comprehend the use of standard units in measurement.
- choose a measurement tool and unit that is suitable for the attribute being assessed.
- repeat a single unit measurement to get a measurement of something bigger than the unit (e.g., measuring a room's length with a single meter stick).
- utilize instruments for measuring.
- create common referents for measurements so that estimates and comparisons can be made.

- How can we determine whether it's better to estimate or to use mental math to get an exact answer? 
- How is the length measured?

- Estimate: A smart guess

- Loreen Leedy. (1997). Measuring Penny. Henry Holt & Co.
- suggested classroom objects to be placed at stations: stapler, three-hole punch, ink marker, bookshelf, door
- copies of Lesson 3 recording pages printed back-to-back (M-2-7-3_Lesson 3 Recording Page)
- 3" x 3" sticky notes
- measuring tools for workstations, five of each: centimeter rulers, decimeter rods (or use the tens from base-ten blocks; most are ten centimeters long), and meter - sticks
- pencils, one for each group

- One way to evaluate students' comprehension of object measurement is through the Lesson 3 Recording Page (M-2-7-3_Lesson 3 Recording Page). Additionally, it will help identify which students might require more practice measuring length.
- Students' comprehension of resolving length-related problems and comparing objects can be evaluated using the word problems on the second page of the Lesson 3 Recording Page resource (M-2-7-3_Lesson 3 Recording Page).

Explicit instruction, modeling, scaffolding, and active engagement
W: Go over the recommended reading. Make a chart with the common units of measurement. When discussing the appropriate applications for each type of unit, stress that measurement always needs to have a unit indicated. 
H: Set up stations with items to measure in meters, decimeters, or centimeters all over the room. To measure the objects, each group will only use one of the provided units of measure. 
E: Assign each group in the class a page containing the list of objects to be measured. As the groups move from station to station, make sure you walk around to ensure everyone is measuring correctly and using the right unit. 
R: Convey the students' findings back to their desks. Before disclosing their unit measurements, groups can speculate as to which measurement the other groups used and talk about any discrepancies they may have had. 
E: Discuss the difficulties of measuring an item that is much smaller or larger than the measuring unit. Make the point that larger objects should be measured with larger measuring units and smaller objects with smaller measuring units. When an object is measured in a smaller unit, its measure will be larger than when it is measured in a larger unit. 
T: Students will finish the measurement sheet in pairs by applying effective methods for calculating sums and differences. (M-2-7-3_Recording Page for Lesson 3) 
O: This lesson starts with a review of the standard units and nonstandard units that can be used to measure length. After that, students have the chance to measure the length of objects in the classroom using a common measuring tool. As students present their measurement numbers, their peers are tasked with connecting the number to a unit, necessitating that they weigh the unit's dimensions against the object being measured. Students will learn the importance of a referent when measuring through a discussion at the end of the class. When expressing length or other measurements, it is imperative to specify the units that were used.

In advance: Before covering the box with a sticky note, circle one of the units at the top and set up a recording page for every group of three to four students. Ensure that at least one group uses each unit of measurement. Set up five stations around the room, each containing one of the recommended classroom items and equipped with a meter stick, decimeter rods, and a centimeter ruler.

Check out Loreen Leedy's book Measuring Penny, if it's available. This is the tale of a young woman who receives an assignment to measure something in as many ways as she can. It serves as a useful starting point for conversations regarding the use of standard and nonstandard units as referents in measuring. Lisa evaluates several traits in both her dog Penny and other dogs, showing how she applies a different unit to each trait. She measures the dogs' ears with cotton swabs and their paw prints with centimeters, for instance.

Following your reading and discussion of the narrative, make a chart with the labels "Standard Units" and "Nonstandard Units." Students can still complete this chart using the prior activities in this unit, even if they are unable to read the book first.

Ask students to list the different instruments that can be used to measure an object's length and ask them to indicate whether these instruments belong under the "Nonstandard Units" or "Standard Units" heading. Verify that you understand the definitions of "standard" and "nonstandard." Talk about the appropriate uses for each type of unit.

It is crucial to realize that we must use a unit of measurement when discussing our measurements.

"Would we understand what Lisa meant if she said her dog's ear was '1' long? Does she mean one inch? One foot? Just one pencil? We don't know, so we'd all have different ideas about the length of the dog's ear.

"Today, we will measure the objects I have placed at the stations around the room using standard units. Moreover, three measuring instruments will be available at each station. Each team will use only one of the tools. I'll give you the list of items. You will notice a sticky note at the top of the page listing the objects. Check the note underneath it to determine the appropriate unit to use while measuring. Keep the note on your paper to protect your unit's identity." Since the groups will be using different units, they will also be using different tools. While you are working, avoid talking to other groups because they will try to figure out which unit you are using later. To give students a chance to use a variety of tools, repeat the activity.

Hold up each measuring tool and say, "If your unit is centimeters, you will use the centimeter ruler. You will use the decimeter rods if your unit of measurement is a decimeter. You will also use the meter stick if your unit is a meter. On the line, write the number of units that correspond to each object's length. Write something like "about 8" if the object is shorter than your unit, or something like "about 5" if it is longer. Keep in mind that you should avoid conversing with other groups while working."

Assign students to groups of three or four. Assign groups a recording page (M-2-7-3_Lesson 3 Recording Page) containing a list of objects with the unit they will use circled at the top and protected with a sticky note. Each group will require a pencil. Assign groups to stations and demonstrate to them how to move around the space so that every object is measured.

Give the groups time to work together. Move around the room while taking measurements to make sure the groups are utilizing the instruments correctly and consistently. It might be necessary to give the groups utilizing meter sticks some guidance on how to measure small items like crayons or staplers. Make them say "zero" or "a small part" of a meter instead of allowing them to use the centimeter markings. Students should round up to the nearest whole unit when measuring.

When they're done, get the groups back together to discuss the findings. Request that one student from each group share the numbers associated with each item, being cautious not to disclose the unit of measurement. Students should think-pair-share to determine which unit the sharing group used, then assign them to the other groups. Select a few students to share their unit guesses along with their justifications.

Alternatively, have each group share without speculating. Then, have them find other groups that they believe use the same units (e.g., centimeters with centimeters) by getting them to stand up. After they have compared and discussed any differences in their numbers, let them show you their units.

Discuss the difficulties that groups encountered when measuring an object that was significantly longer or shorter than the measuring units assigned to them. How would they select the most suitable unit if they had to measure the same objects again using any of the units? Which items would be the most appropriate to measure in centimeters? Decimeters? Meters? Why? Teach students that it is best to measure larger objects with larger units and smaller objects with smaller ones.

Guide the students to see the inverse relationship between the numerical measure and the unit's size. Use examples from their work. When a bookshelf is measured in decimeters rather than meters, a higher number is obtained. Numerical measures are inversely related to larger units and positively related to smaller units.

Teach students how to solve measurement problems by using addition and subtraction. Teach students to solve measurement addition and subtraction problems in pairs (M-2-7-3_Lesson 3 Recording Page) or allow them to choose their partners.

As a class, discuss strategies, and then have partners compare their responses to those of other groups.

Extension:

Routine: List or show three measuring units along with an object displayed in the classroom. Use one of the units to write a number that indicates how much you measured that object. Encourage students to identify the unit they believe you used to measure the object and provide an explanation or illustration in their math journals. As an illustration, you might put up a poster and write "centimeters, hands, feet" on the board. Next, write "3 _______." For example, students could write "3 feet" and state, "The poster is very long, with feet being the largest unit." The centimeter would be insufficient. Select distinct items and measurements for other days.

Small Group: Students who could use more practice can use this activity. Cut twelve-inch (approximately one-inch-wide) paper strips for the classroom. Present a piece of paper to every student. Ask them to remove a piece about 4 inches in length without using a ruler. If the first piece is 4 inches long, then ask how long the remaining piece should be (about 8 inches). For measuring the first piece, have a ruler available. "Is it four inches in length? If not, how many inches is it? What is the expected length of the remaining piece, if it is 4 inches or less? Measure to find out. Attempt to tear off one inch from the longest piece. What should the lengths of your three sections be? Measure to find out. In total, 12 inches will be obtained by adding the lengths of all three. How many times did the group split a 12-inch piece into three pieces? What else could we say about them?"

Expansion: This activity can be used with students who are ready for a more difficult task. At each workstation, place scissors and a ball of string. Additionally, supply several measuring implements, including both conventional (such as yardsticks, rulers, meter sticks, and tape measures) and unconventional (such as pencils, index cards, or straws). Students should cut a length of string equal to an object they have chosen from the classroom. Back at the workstation, measure the string with four or five of the available measuring instruments and units. Ask students to use the lengths of their strings as a reference to describe the lengths of the items in the classroom.