Lesson 2

In the previous lesson, students ordered three objects by length by lining them up at their endpoints. Students used complete sentences to describe the relative length of objects.

The purpose of this lesson is for students to compare the length of two objects indirectly by comparing them with the length of a third object. Indirect comparison allows students to compare the length of objects that are difficult to compare by lining them up. The ideas in this lesson lead to the understanding that iterated length units can be used to measure and compare the length of objects. Students may intuitively understand the concept of indirect comparison and this lesson provides an opportunity for them to develop language to communicate that understanding (MP6).

Activity 2: Measure Your Desk

• Each group of 4 students needs access to the materials from the previous lesson and one unsharpened pencil.
• Create a two-column chart with the headings “longer” and “shorter” for the synthesis.

• Each group of 2 needs a piece of string longer than the length of the side of the students’ desks shown in the activity.