In previous lessons, students ordered a set of three objects by length. Students also compared lengths of objects indirectly by using a third object.

The purpose of this lesson is for students to describe lengths of objects in terms of connecting cubes. Students measure by using connecting cube towers because the units are lined up without gaps or overlaps, a concept students will explore in future lessons. In the first activity, students use connecting cube towers to measure the lengths of different animals. Students build towers that are exactly the same length as each animal and make a comparison statement, such as “The grasshopper is the same length as a tower of 7 cubes.” In the second activity, students use connecting cube towers to measure the lengths of more animals and describe each length as “___ cubes long.” Even though the side-length of the cube is the unit, it’s appropriate for students to describe length in terms of “X cubes long.” This transition in language helps students understand that the length of an object can be described as a number of length units (MP6). In this lesson, the length unit is the length of a single connecting cube.