Outdoor Science Education and Child Well-being in Primary Schools: Protocol for a Cluster Randomized Controlled Trial on Learning, Connection to Nature, Eco-anxiety, and Stress

Students' scientific observation skills will be assessed using a structured observation rubric designed for elementary science education. After the 5-week intervention, each student will spend one day in a new environmental context (field activity at the end of October). Students will be asked to make a total of five oral observations of living organisms in this setting. Independent raters, trained in the use of the rubric, will evaluate the quality of each scientific observation using a four-level scoring framework, with scores ranging from 0 (lowest) to 3 (highest quality of scientific observation). The total score will range from 0 to 15, with higher scores indicating stronger scientific observation skills. Inter-rater agreement will be monitored to ensure reliability.

Students' connection to nature will be assessed using the Inclusion of Nature in Self Scale (Schultz, 2001, as used in Braun & Dierkes, 2016), a validated 1-item self-report questionnaire appropriate for culturally and ethnically diverse samples of children. The item is rated on a 7-point scale (1 = nature and self do not overlap at all to 7 = nature and self completely overlap). The total score ranges from 0 to 7, with higher scores indicating a stronger subjective connection to nature. The Inclusion of Nature in Self Scale will be administered at baseline and again immediately after the 5-week intervention.

Students' perceived stress will be assessed using the Perceived Stress Scale for Children (PSS-C), which is a standardized 13-item self-report questionnaire previously tested on a sample of Canadian children (White, 2014). Each item is rated on a 4-point Likert scale (0 = never to 3 = a lot). Scores are summed to produce a total ranging from 0 to 39, with higher scores indicating greater perceived stress. The questionnaire will be administered in class at baseline and immediately after the 5-week intervention.

Students' eco-anxiety will be assessed using the Hogg Eco-Anxiety Scale (HEAS-13; Hogg et al., 2021), a validated 11-item self-report questionnaire. Each item is rated on a 4-point Likert scale (0 = never to 3 = almost every day). Scores are summed to produce a total ranging from 0 to 33, with higher scores indicating greater subjective feelings of eco-anxiety. The HEAS-13 will be administered in class at baseline and immediately after the 5-week intervention.

Students' satisfaction of the three basic psychological needs identified by Self-Determination Theory (autonomy, competence, and relatedness) will be assessed with a 9-item version of the Basic Psychological Needs Satisfaction Scale, adapted for children. Each item is rated on a 5-point Likert scale (0 = almost never to 4 = almost always). Total scores range from 0 to 36, with higher scores indicating greater satisfaction of basic psychological needs.