In this lesson, students add and subtract within 20 and build fluency within this range of numbers. They also practice measuring lengths in centimeters and use their measurements to add and subtract. The activities encourage students to consider ways to use properties of operations to create "easier" or known expressions (MP7).

In the first activity, students measure lengths on a map and add and subtract their measurements to answer questions. They share the ways they used facts that they know to find the value of sums and differences. The questions focus on the measured distances in centimeters. It may be helpful to discuss how the actual distances between cities are much longer. However, proportional relationships, such as those in a map scale, is a grade 6 topic and should not be the focus of these activities. In the second activity, students solve Compare problems within the context of their measurements on the map.

The Cool-down should be completed before the Lesson Synthesis so that students can share their responses during the Lesson Synthesis.