Its goal is to increase physical activity and reduce sedentary behaviour during the school day, improving physical and mental health, cognition, and academic performance. A two-arm randomised controlled pilot trial (intervention and control groups) will be conducted, involving four schools. Two schools will be randomly assigned to the intervention group, where the MOVI-Play&Learn programme will be implemented, and two to the control group, where usual classroom activities will continue throughout the 2026–2027 academic year. The implementation includes two active breaks of approximately five minutes per day, five days per week, among fifth- and sixth-grade primary school students, accompanied by teacher training and technical support. Two assessments (baseline and post-intervention) will be carried out to measure the study variables (in-class activity/sedentary behaviour, physical fitness, body composition, mental health, quality of life, cognition, and academic performance), along with a qualitative study on acceptance and usage.