the purpose of this research was to determine whether parental involvement in a physical activity intervention delivered to children in-school could result in positive behaviour change in parents (“spread of effects”), as measured by increased levels of physical activity and reduced sedentary behaviour. a sequential explanatory mixed methods design was used, consisting of a randomized control trial followed by phone interviews using nested sampling from the original population. fifth grade 世界杯2022赛程表淘汰赛 (n = 27) from eight classrooms and one respective parent/guardian for each student participated in the study as pairs. classrooms were randomly assigned to the control or experimental treatments. all 世界杯2022赛程表淘汰赛 received a turnoff week challenge tracker form to encourage 世界杯2022赛程表淘汰赛 to increase their physical activity and reduce their screen time behaviour. both experimental and control student-parent/guardian pairs each completed an online pre- and post measure of physical activity and sedentary behaviour (rapid assessment of physical activity [rapa] and physical activity questionnaire for older children [paq-c] respectively). student-parent/guardian pairs in the experimental group were assigned two homework assignments in order to facilitate parental involvement in the intervention and possible indirect treatment effects (“spread of effects”). phone interviews (n=17) were completed with interested parents/guardians. using thematic network analysis, the interviews furthered explored how children may influence their parent/guardian’s physical activity levels and to increase understanding of how spread of effects can occur in health education interventions.