The purpose of this activity is for students to compare two lengths indirectly. Since a third object is not given, students choose a third object strategically and share different ways to use a third object to compare (MP5).

Students choose from a variety of objects, such as connecting cube towers, pieces of string, and unsharpened pencils. As students compare the lengths of the paths, they may use a single tool, such as a piece of string. They may mark or cut the string. Some students may choose the tower of connecting cubes and determine that breaking off or counting the cubes is a way to determine whether one length is shorter or longer than the other. Others may select and try different tools until they find one that has a length that is in between the length of the two paths.

• Invite previously identified students to share.
• “How was using a tool helpful to compare the lengths of the paths?” (We couldn’t put the paths next to each other so it was helpful to have a tool that could be moved from one path to the other to compare.)

The purpose of this activity is for students to compare the lengths of two objects using a third object. When students decide if the teacher's desk will fit through the door or compare other large pieces of furniture, they need to be precise about which lengths they are measuring, as objects like the teacher's desk, a rug, and a bookcase, have a length, width, and a height (MP6). Next, students need to select an appropriate third object to use to compare the lengths they have chosen. Teachers may choose to assign different questions for different groups to start with to facilitate student movement around the room. Teachers may also change any question that does not apply to their classroom.

• Invite previously identified students to share.
• For each student, ask: “How did they compare the lengths of the objects? What tool did they use? What part of each object did they measure?”