Health literacy is a key determinant of children's health and well-being, enabling them to access, understand, evaluate, and use health information to make informed health-related decisions. Middle childhood represents a critical developmental period for strengthening these competencies; however, evidence regarding theory-based school interventions designed to improve health literacy in this age group remains limited.

This cluster randomized controlled trial aims to evaluate the effectiveness of a six-week, theory-based school health literacy program developed for children aged 9-10 years. The intervention was designed by integrating Nutbeam's Health Literacy Model and Piaget's Theory of Cognitive Development and incorporates interactive, child-centered educational strategies, including educational games, storytelling, role-playing, problem-solving activities, and classroom discussions. Third- and fourth-grade students attending public primary schools in Burdur, Türkiye, were randomly assigned at the school level to either the intervention or control group. Health literacy outcomes are assessed using the Health Literacy Survey Questionnaire for Children-Turkish Version (HLS-Child-Q15-TR) before and after the intervention. The findings are expected to provide evidence regarding the effectiveness of theory-based school health literacy interventions and to inform future school health promotion programs.

Health literacy is recognized as a fundamental determinant of lifelong health and well-being. Childhood represents a critical period for the development of health literacy competencies because children begin to acquire the cognitive, social, and behavioral skills necessary to access, understand, evaluate, and apply health information in everyday life. Despite growing international interest in promoting health literacy among children, evidence regarding theoretically informed school-based interventions remains limited.

This study evaluates a theory-based school health literacy intervention developed for primary school children aged 9-10 years. The intervention was designed by integrating Nutbeam's Health Literacy Model, which conceptualizes health literacy as functional, interactive, and critical competencies, with Piaget's Theory of Cognitive Development, emphasizing learning strategies appropriate for children in the concrete operational stage. The program incorporates child-centered educational approaches, including educational games, storytelling, role-playing, problem-solving activities, visual materials, classroom discussions, and real-life scenarios to facilitate active learning and the application of health information.

The intervention consists of six weekly classroom sessions delivered over a six-week period. The effectiveness of the program is evaluated using a cluster randomized controlled trial conducted in public primary schools in Burdur, Türkiye. Health literacy is assessed before and after the intervention using the Health Literacy Survey Questionnaire for Children-Turkish Version (HLS-Child-Q15-TR). The findings are expected to contribute to the evidence base for theory-based school health literacy interventions and support the development of effective school health promotion programs for children.

Inclusion Criteria:

• Children aged 9-10 years.
• Enrolled in the third or fourth grade of a participating public primary school.
• Able to understand and complete the study questionnaires.
• Written informed consent obtained from a parent or legal guardian.
• Child provided verbal assent to participate.

Exclusion Criteria:

• Participation in a structured health literacy education program with similar content within the previous 6 months.
• Inability to participate in the intervention sessions because of prolonged absence from school.
• Attendance at <80% of the intervention sessions.
• Withdrawal of parental consent or child assent at any time during the study.

The datasets generated and/or analyzed during the current study are not publicly available because they contain potentially identifiable information from child participants but are available from the corresponding author upon reasonable request and with permission from the relevant ethics committee.

Blinding was not feasible because the educational intervention was delivered directly to students in the classroom by the principal investigator. Consequently, participants, investigators, and outcome assessors were aware of group allocation.