This Problem Set is a part of the Lesson 1, Unit 3, Grade 1. This lesson begins extending students' Kindergarten experiences with direct length measurement to indirect measurement whereby the length of one object is used to compare that of two other objects. Students explore direct comparison, comparing the length of two objects by paying close attention to the endpoints of each to ensure accurate comparisons. They draw on their Kindergarten experiences as they use "longer than" and "shorter than" as they compare.