PLAY UP: An Intervention Program Through Active Play and Environmental Affordances

Motor competence, as an indicator of physical literacy, will be assessed using the Movement Assessment Battery for Children - Second Edition (MABC-2; age band 1). Movement ABC consists of 3 subtests that measure three different areas: manual dexterity; aiming and catching; and balance. Raw scores obtained in each task are converted into age-standardized scores according to the norms provided in the MABC-2 manual. The MABC-2 total standardized score is derived from the manual dexterity, aiming and catching, and balance domains.

Preschool and Kindergarten Behaviour Scale (PKBS), completed by preschool educators, evaluates children's social-emotional skills and behavior problems during free play with their peers. The instrument is organized into two main scales: (i) the Social Skills Scale divided into three dimensions - Social Cooperation, Social Interaction, and Social Independence; and (ii) the Problem Behavior Scale divided into two subscales - Externalizing Behavior Problems and Internalizing Behavior Problems. The PKBS Social Skills Scale score and Problem Behaviour Scale score will be used. Higher scores on the Social Skills Scale indicate stronger social-emotional competence, whereas higher scores on the Problem Behaviour Scale indicate greater behavioural concerns.

Children's behavioural difficulties will be assessed using the Strengths and Difficulties Questionnaire (SDQ; ages 4-17 years), a 25-item psychosocial questionnaire completed by parents, designed to assess children's strengths and difficulties, providing behavioural indicators of potential mental health problems. The SDQ total difficulties score will be derived from the sum of the four problem subscales - Emotional Symptoms, Conduct Problems, Hyperactivity/Inattention, and Peer Relationship Problems - and interpreted according to predefined cutoffs as normal, borderline, or clinically significant.

Key executive functions inhibitory control, cognitive flexibility, and working memory will be assessed using the Head-Toes-Knees-Shoulders (HTKS) task. Task performance also relies on the child's sustained attention. The total HTKS score will be used as a single composite score reflecting executive functioning, including inhibitory control, cognitive flexibility, working memory, and sustained attention. A higher score reflects a better executive functioning.

Spatial Activity Behaviour (SAB) will be assessed as the spatial distribution of physical activity intensity during outdoor recess. This outcome will be derived from synchronised accelerometry and Global Positioning System (GPS) data. The reported value will describe where different physical activity intensities occur within the kindergarten outdoor environment.

Child-Level Positional Interactions (CLPI) will be assessed using real-time spatial positioning tracked over approximately 30 minutes during outdoor recess using high-resolution sensor technology. This will allow the capture of detailed movement trajectories and interpersonal positioning in the playground environment. Outcomes will include mean inter-child distance and frequency of proximity interactions during recess.

Kindergarten affordances for physical literacy (KAPL) will be assessed using the GO-Exterior instrument and Photo Elicitation Interviews. The GO-Exterior instrument includes a structured observation grid of the outdoor environment and a semi-structured interview with the educator, allowing the calculation of category-specific and overall scores related to outdoor environmental quality, action opportunities, adult role, and routines. Photo Elicitation Interviews will be conducted with children to explore their enjoyable experiences, appreciation, connection to the environment, preferences, perceived physical and social affordances, and experiences related to movement, play, and physical activity.

Feasibility will be assessed using recruitment, retention, participation, attendance, and adherence rates, as well as the feasibility of assessment procedures and intervention delivery. Indicators will include the number/proportion of eligible children recruited, intervention sessions delivered as planned, and children attending/participating in the intervention sessions.

Acceptability will be assessed from the perspectives of children, educators, and the research team. Indicators will include children's engagement, participation, and perceived enjoyment, as well as educators' and researchers' perceptions of the suitability and acceptability of the intervention. Data will be collected through observational records and semi-structured interviews with educators and children.

Implementation quality will be assessed by examining intervention dose, intensity, duration, fidelity to planned procedures, resources required, barriers and facilitators to implementation, and safety, including monitoring and reporting of adverse events. Data will be collected through research team records, observation logs, and educator feedback.