Measurement comprises an important set of concepts that are fundamental for students to competently navigate and work with objects and structures within their physical environment. Despite their importance, these concepts are difficult for students to grasp, as evidenced by low performance on measurement items on the National Assessment of Education Progress (NAEP). In particular, students seem to have difficulty understanding the concept of length. In this article, the authors describe five activities to support elementary school teachers in building students' conceptions of measurement. They begin by briefly reviewing the relevant Common Core State Standards for Mathematics (CCSSM) and key concepts essential for understanding length.