This is a prospective, school-based randomized controlled trial designed to evaluate a wearable device-supported outdoor activity program for myopia prevention in primary school students with adequate hyperopic reserve. Enrolled students in grades 1 to 4 will be randomly assigned to either a wearable device-supported outdoor activity program plus routine school-based eye health education or routine school-based eye health education alone. Outcomes will include changes in axial length and cycloplegic spherical equivalent refraction, incident myopia, intervention adherence, and safety outcomes over 12 months.