Future School of Comprehensive Well-Being

Connor-Davidson Resilience Scale (CD-RISC, 10 items). Comprises 25 items, each rated on a 5-point scale (0-4). Range from 0 to 100, with higher scores reflecting greater resilience.

Anxiety and depressive symptoms; Revised Child Anxiety and Depression Scale (RCADS, 25 items). The RCADS-25 has 25 items, each rated on a 4-point Likert scale (0 = Never, 1 = Sometimes, 2 = Often, 3 = Always). Therefore, the total raw score can range from 0 to 75 (25 items × 3 points each). Higher scores indicate more symptoms of anxiety or depression.

The World Health Organization-Five Well-Being Index (WHO-5) (5 items). Each item is rated on a 6-point Likert scale. The total raw score range is 0-25; higher scores indicate better well-being.

Study burnout scale (7 items). Each item is rated on 7-point Likert scale (Totally disagree = 1, Totally agree =7), with higher scores reflecting higher risk for study burnout.

Bergen Social Media Addiction Scale (BSMAS, 6 items)

The Classroom Peer Context Questionnaire (CPCQ, 20 items). Each item is rated on 7-point Likert scale (Totally disagree = 1, Totally agree =7), with higher value indicating better fit and atmosphere.

Peer support scale (10 items). Each item is rated on 7-point Likert scale (Totally disagree = 1, Totally agree =7), with higher scores reflecting greater peer support for studying.

Empathy towards peers scale (9 items)

Teacher support scale (11 items). Each item is rated on 7-point Likert scale (Totally disagree = 1, Totally agree =7), with higher scores reflecting greater teacher support.

Guardian support scale (7 items). Each item is rated on 5-point scale assessing frequency (1 = never, 2 = rarely, 3 = sometimes, 4 = quite often, 5 = very often), with higher scores reflecting more frequent guardian support.

The 20 m shuttle run test. Participants are required to run continuously between two lines set at a distance of 20 m, keeping cadence with a recording (beeps) that increases in pace as the test progresses. The total number of shuttles (laps) achieved while keeping to pace is recorded.

The curl-up test. Participants are required to lie on their back, keep heels on mat, and slowly curl up, while curling up sliding fingertips across a measuring tape until reaching the other side, and then curl back down until their head touches the mat. The length of the measuring tape is 8 cm at grade 5 and 12 cm at grade 8. Performance cadence is guided by a recording. The total number of curl-ups (min, 0; max, 75) completed correctly while keeping in time with the cadence recording is recorded.

The push-up test. The test has different protocols for boys and girls. The boy's starting position requires hands and toes to be on the floor, whereas the girl's starting position requires hands and knees on the floor. All other steps for the test are the same for both sexes: head, body, and legs are in a straight line; feet together; arms shoulder-width apart; body lowered until there is a 90° angle in elbows; upper arm parallel to the floor; and back and knees straight while pushing up, until the arms are straight. The total number of correctly completed push-ups in 60 s is recorded.

A composite score comprising four measurements (squat, lower back extension and left and right shoulder stretch) assessing multi-joint flexibility. The maximum score in flexibility is 4 and minimum 0.

Squat: squatting as low as one can while keeping his/her back extended, arms raised straight up, knees behind the toe line, hip angle above 45°, heels on the ground, and feet and knees shoulder-width apart. A result of 1 is recorded if participant reaches a knee angle ≤ 90° and 0 if the knee angle is > 90° and/or participant cannot keep the proper position.

Lower back extension in sitting posture: Results are marked as 1 if participant's lower back is extended and as 0 if the lower back is not extended and/or participant cannot keep the proper position.

Shoulder stretch: Results are marked as 1 if participant can reach his/her fingers together between shoulder blades and as 0 when participant cannot reach his/her fingers together and/or participant cannot keep the proper position.

The throw-catch test. A target square (1.5 m × 1.5 m) is marked on a wall at 90 cm above floor level. Throwing distance depends on the participant's grade and sex (7 and 8 m at grade 5, and 8 and 10 m at grade 8, respectively, for girls and boys). Participants are instructed to throw a tennis ball with their preferred hand directly at the target and to catch the ball after one bounce with one or both hands. Participants are allowed 20 trials, and the result is the number of successfully completed trials (i.e., the ball hit the target and was caught after one bounce).

The 5-leaps test. The 5-leaps test consists of five consecutive strides with feet together at the start and end of the five leaps sequence. Participants are allowed to start the strides with their desired leg. The test is performed twice, and the better result (that is, the overall distance covered in meters rounded to two decimal places) is recorded.

One item "What do you think about your current health?" The item is rated on a five-point Likert scale (1= very good…5 = very bad).

The Finnish version of the sport competence dimension of the Physical Self Perception Profile (PSPP). Each item is preceded by the stem:" What am I like?" and all five items of the PSPP are rated on a five-point scale (e.g., 1 = I'm among the best when it comes to athletic ability … 5 = I'm not among the best when it comes to athletic ability).

Hip-worn accelerometers (ActiGraph GT3X+, wGT3X+, Pensacola, Florida, USA) during waking hours for 7 consecutive days. Participants are instructed to always wear the device on their right hip during their waking hours, except while bathing or doing water-based activities. Data are collected as raw accelerations at a frequency of 30 Hz and converted into 15-s epoch counts. Customized Visual Basic Macro for Excel software is used for data reduction. A valid day of physical activity monitoring includes measured values ≥600 min/day for at least two weekdays and one weekend day between general waking hours (i.e., 7 am and 11 pm). Periods of 30 min of consecutive zero counts are defined as non-wear time, and values over 20 000 counts per minute (cpm) are considered spurious accelerations and discarded. Cut points are used to calculate MVPA (≥2296 cpm).

Grade 8 students' physical activity and sedentary time is measured using a thigh-worn accelerometer (Axivity AX3, York, United Kingdom) 24-hour a day for 7 consecutive days. Data are collected in raw 100 Hz acceleration with range 8 g. ActiPASS (version 1.62) is used for data reduction and analyses. The valid amount of data is set at ≥10 hours/d, including at least 2 weekdays and 1 weekend day.

A two-item self-report scale. The stem for the items is: 'In the next two questions physical activity means all activities which raise your heart rate or momentarily gets you out of breath for example in doing exercise, playing with your friends, going to school, or in school physical education. Physical activity also includes for example jogging, intensive walking, roller skating, cycling, dancing, skating, skiing, soccer, basketball, and baseball.' The items are: 'Think about your typical week. How many days did you exercise for at least 60 min. during which you got out of breath' and 'Think about your last 7 days. How many days did you exercise for at least 60 min. during which you got out of breath?'. Both items are presented using an eight-point response scale (0 to 7 days in a week). A sum-scale of physical activity is computed by calculating a mean score for the two items.

Collective learning agency; Collective learning agency scale (13 items). Each item is rated on 7-point Likert scale (Totally disagree = 1, Totally agree =7), with higher scores reflecting greater collective learning agency.

Grade Point Average (GPA) and grades in each school subject and in behavior.