Most of the existing ecological studies have been conducted during class instructional time. The purpose of this qualitative study was to describe (a) how students (N = 102; grade 2–4) engaged in a strategy named Health Passport taking place mainly outside of school time and (b) how four physical education teachers held students accountable for their involvement in physical activity during a long period of time (3–7 months). An inductive approach guided the data analysis, based on observational notes, interviews, and the content of the students’ Health Passport. The results indicated that children displayed five different profiles of involvement in the completion of the tasks related to their passport. Physical education teachers chose to trust students’ self-management capacity instead of using a formal evaluation to hold them accountable. The experiment of the Health Passport showed that physical education teachers can put together and implement accountability strategies to support students’ regular practice of physical activity at home.