In previous lessons, students measured lengths and determined how much longer one object is than another using centimeters. They have also developed strategies for adding and subtracting numbers within 100.

This lesson combines these skills. Students interpret story problems about length measurements whose solution requires addition and subtraction within 100. In each activity, students solve Compare problems in situations where the language of the problem may direct students to use an incorrect operation. Throughout the lesson, they are encouraged to make sense of and use tape diagrams to visualize the measurement contexts and make sense of the lengths and their relationships (MP1, MP2).