This lesson is optional because it is an opportunity for extra practice that not all classes may need. In the first activity, students learn Stage 1 of the Creating Line Plots center. In this stage, called Inches and Centimeters, students measure up to 8 objects to the nearest centimeter or inch. They work with a partner to create a line plot to represent their measurement data. Then they ask their partner 2 questions that can be answered based on their line plot. In the second activity, students choose to continue working on Creating Line Plots, or choose between two previously introduced centers focused on estimation and measurement or a center focused on addition and subtraction.