Schools are critical settings to foster children's health. The purpose of this two-year cluster-randomized trial is to enhance both the after-school and recess settings to provide children with knowledge and skills to facilitate active and inclusive play. The primary aim of the project is to assess the impact of a playground curriculum intervention on children's physical, social, emotional, and behavioral health. The secondary aim of the project to understand the appropriateness, feasibility, fidelity, and sustainability of implementing a playground curriculum in after-school and recess settings.

Physical, social, and emotional health are critical for children and predict good health later in life. Schools are essential settings to foster children's health as they provide access to the majority of children during crucial stages of development. In particular, recess and before/after school programming are critical sources of children's health and well-being, and core components of a whole school approach to health and wellness. The purpose of this two-year cluster-randomized trial is to enhance the quality of these existing settings through the integration of a playground curriculum designed to promote active and inclusive play.

Based on Social Cognitive Theory aligned with the Theory of Expanded, Extended, and Enhanced Opportunities, it is hypothesized that active and inclusive play through a playground curriculum intervention will improve enjoyment, knowledge, and self-efficacy (personal conditions), social and emotional learning (behavioral conditions), and the development of peer relationships (environmental conditions) among children, leading to increased physical activity and reduced behavioral incidents. The implementation (appropriateness, feasibility, fidelity, and sustainability) of the playground curriculum intervention to improve children's health will be assessed as a secondary outcome.

Participants will be recruited from elementary schools in Mesa Public Schools (Arizona) that offer after-school programming (N=14). The intervention includes the delivery of a curriculum aimed at providing students with knowledge and skills to initiate activities using playground structures. Trainings will be delivered to staff (after-school staff, recess aides, and Physical Education teachers) and students in the after-school setting. Students attending the after-school program will become Play Leaders to transfer the knowledge and skills they learn from PlayOn! to the recess setting.

The impact of the playground curriculum intervention on children's physical, social, emotional, and behavioral health after school and during recess will be measured using surveys, observations, interviews, physical activity devices, and de-identified school behavioral information. Data will be collected at all 14 school sites each fall and spring semester. In year one, seven schools will receive the intervention. Schools will be stratified to either the intervention or control group by Title 1 status - an indicator of school-level income. In year two, the seven control schools will receive the intervention to allow all schools the opportunity to benefit from the project.

Inclusion Criteria:

• Students enrolled an after-school program in Mesa Public Schools

Exclusion Criteria:

• Students in grades kindergarten or first grade will be excluded due to their young age.

All IPD that underlie results in a publication will be de-identified and available

Data will become available 6 months after publication and remain available as stored in repository

A link to an open-access data repository will be included in all publications. Interested parties can also contact the principal investigators of the study for data access.