Physics sensemaking is a growing topic of study within the physics education community. Many lenses have been used to study sensemaking but few have considered how time and instruction can impact student sensemaking practices and ideas. In this dissertation, I present four studies that address four major questions: What sensemaking practices do students in lower and middle division physics use? What are instructor’s and students’ ideas about sensemaking? What do students’ claim is most influential to their sensemaking ideas and practices? How do these students ideas about sensemaking change over time? I explore these research questions in four studies: a study of faculty understanding and use of dimensional analysis, a study of introductory physics students responses when asked to make sense of a symbolic answer to a given question, a study of one students ideas about sensemaking and sensemaking habits, and a longitudinal study about three student’s sensemaking ideas during and after explicit sensemaking instruction. I have found that students engage in many sensemaking practices. The main sensemaking strategies students used varied with the course they were taking when they were interviewed. While enrolled in introductory physics with calculus, students made sense of a given solution by checking units/dimensions, drawing pictures, and reasoning about functional dependence. While enrolled in higher-level physics courses students reported using the same strategies as those in introductory physics but also did special-case analysis, proportional reasoning, graphing, and solving problems more than one way. Students’ ideas about sensemaking vary widely, from believing sensemaking is a tool to check an answer to viewing sensemaking as essential way of reasoning. I also found that sensemaking is often taught though example, with little to no explicit instructional support. One study presented in this dissertation analyzed a course, Mechanics, which supported sensemaking explicitly. I investigated student ideas about sensemaking while they were enrolled in Mechanics and found that explicit sensemaking instruction had a large impact about their ideas. I also found that students’ sensemaking ideas evolved from the belief that sensemaking was a tool for checking an answer into the belief that sensemaking is a lens for interpretation. Based in these results, I call for research on how sensemaking practices are related to physics identity and for instructors to move toward more explicit instruction on physics sensemaking strategies.