Lesson 7

The purpose of this lesson is for students to measure lengths of objects using different length units and understand that the number associated with a length depends on the chosen unit.

In previous lessons, students were given a length unit to use to measure the lengths of different objects. In this lesson, students choose different length units to measure the same object and describe what they notice about the measurement of an object when different length units are used. In the first activity, students measure a strip of tape on the floor with three different length units. They see that they get different measurements depending on the unit they use. In the second activity, students are presented with examples of how different students measured the length of a shoe. Students determine if the shoe was measured correctly or incorrectly and why. Students learn that in order to describe the length, one needs to choose a single length unit. In the lesson synthesis, students evaluate the appropriateness of different units to measure different objects.

• Create sets of 30 connecting cubes, 50 base-ten cubes (centimeter cubes), twenty 2-inch paper clips, and twenty 1-inch paper clips for each group.
• Put 18-inch strips of tape on the floor for each group. 

Who got to do math today in class and how do you know? Identify the norms or routines that allowed those students to engage in mathematics. How can you adjust these norms and routines so all students do math tomorrow?