• Your observations during the lesson activities and classroom discussion may be used to determine if students comprehend the material.
• The Lesson 3 Assessment (M-1-5-3_Lesson 3 Assessment.doc) may be used to further assess student mastery.

Note: If students don’t have previous experience working with modeling clay, give them time to work with some modeling clay to practice making “snakes.”

“Today we will continue to measure objects. We are going to measure the objects in a slightly different way. Let’s review how we have previously measured objects.” Have a student come to the front of the class and measure the length of an object (tissue box) using multiple instances of a nonstandard unit, such as a large paper clip. Have the class count the number of units placed end to end and report the length of the object. Write the answer on the board. Review with students why it is important to ensure that each new paper clip be placed exactly at the end of the previous one, without leaving gaps or making any overlaps. Discuss why it is important for students to label their answers (e.g., large paper clips). “Now, how could you measure the same object if I only gave you one large paper clip? Let me show you how this could be done.” Use modeling clay to make a snake the length of the object. Explain that the snake has to be exactly as long as the object. Place it along the edge of the object, and starting at one end, use the same paper clip to make an impression in the snake. Move the unit repeatedly, each time making a new impression at the end of the previous one. Have students again report the length referring to the impressions in the snake. “Is this the same length we got the first time we measured the object?”

Discuss the following:

• Why is the number of impressions the same as the number of units counted the first time?
• The modeling-clay snake is a nonstandard measuring tool.

“Now you can do the same activity, but you will work in pairs. You will measure objects using modeling clay and one nonstandard unit.” Distribute to each pair the Measurement Worksheet 2 (M-1-5-3_Measurement Worksheet 2.doc). Give each pair modeling clay and one of each of several nonstandard units, such as a penny, connecting cube, straw, toothpick, paper clip, colored rod, or plastic link. Tell students that they will not be measuring the pictures of the book, shoe, and crayon, but they will measure a real book, shoe, and crayon. Have students repeat the earlier demonstration using clay snakes with their objects. Have each pair of students complete Measurement Worksheet 2 to report their findings. Check students’ progress to ensure that they are measuring correctly, that their snakes are as long as their objects, and that they are placing their units end to end.

Once students have finished the worksheet, bring them back together. “Why did we get different measurements?” Students should realize that their books, shoes, and crayons might be slightly different in length. Also, their measuring unit (e.g., penny versus paper clip) makes a difference.

“Let’s pretend we are going to build something. You measure the length of a board you need using your giant steps. When you get to the lumber yard, you tell the clerk that you need a board 5 giant steps long. The clerk measures the board using his/her own giant steps. What problem could you have?” Lead students to see that the clerk’s giant steps and the student’s giant steps are different, so the steps would result in different lengths. “Long ago people made the same discovery you just made and developed a standard measuring unit. We use standard units so we don’t have problems like the lumber yard. One of those standard measures is the inch. Today, we are going to make our own inch ruler and use it to measure.” This would be a good time to read How Big is a Foot? By Rolf Muller.

Hand out 12 1-inch squares (six each of two different colors) for each student (M-1-5-3_Colored Squares.doc). Or make your own 1-inch colored squares using construction paper.) Have students use the individual 1-inch squares to measure the lengths in the Inch Worksheet (M-1-5-3_Inch Worksheet and KEY.doc).

For example:

After students have finished the Inch Worksheet, ask a volunteer to tell how long the first line is. Have students raise their hands if they had the same answer. “Why are all the measurements the same?” (The unit of measure is the same.)

Distribute the prepared 12-inch strip of tagboard (M-1-5-3_12-Inch Ruler.doc) to each student and have students paste their 1-inch squares in alternating colors, along the edge of the tagboard strip to make their own rulers. Check student progress to make sure students are alternating colors and not overlapping the squares. Fastening the individual units together helps students connect the actual units with the spaces on a ruler. By alternating the colors on the strips, students identify and count the separate units in the continuous configuration. No numbers should be marked on this initial, simple ruler because numbers tend to draw students’ attention to the end points of the units rather than to the intervals. Have students use this simple ruler to measure the objects on the Inch Worksheet 2 (M-1-5-3_Inch Worksheet 2 and KEY.doc); they will also use the simple ruler in the Performance Assessment at the end of the unit (M-1-5_Performance Assessment and KEY.doc).

Remind students that they need to start with the left end of their ruler, and align the object with the edge of the ruler. After students have completed the worksheet, verify that they all have the same answers. Discuss those answers that are different and how students measured their objects. Discuss the advantages of using units that are attached end-to-end.

Once you are finished discussing the results, students can complete the Lesson 3 Assessment (M-1-5-3_Lesson 3 Assessment.doc). The assessment contains two pictures that students need to measure using their simple rulers.

Extension:

• Routine: Cut various lengths of yarn and have students measure the lengths using their simple rulers.
• Small Group: Have students use the Inch Worksheet (M-1-5-3_Inch Worksheet and KEY.doc) and the two colored squares to measure each line and place their colored squares under the line. Have students glue the colored squares down and then use their simple ruler to measure each line. Students should come up with the same answers.
• Expansion: The objects students have been measuring in class are all less than 12 inches long. Have students use their simple rulers to measure objects longer than their rulers. They could also measure distances that are curved.