Protocol for the Open Sky School

The goal of this a randomized controlled trial to test the effectiveness of a nature-based intervention called Open Sky School to reduce mental health problems among elementary school children. More specifically a two-arm clustered randomized controlled trial will be conducted in elementary schools across Québec, Canada. Following informed consent by teachers, parents and students, schools will be randomly assigned 1:1 to the intervention or the control group with a total of 2500 6th grade students and 100 teachers expected to participate. The primary and secondary research questions are as follows.The primary research question :Is the intervention effective in reducing mental health problems in children from pre-to-post test (Social Behavior Questionnaire: self and teacher reports) ?The secondary research questions:Is the intervention effective in improving children's depression, positive and negative affect, nature connectedness. eco-anxiety and pro-environmental behaviors ?Is the intervention effective in improving teachers' well-being and affect ?Are the benefits to children sustained benefits at 3 months follow-up ?Is the primary question moderated by child's sex, child's disability status, the green space of neighbourhoods, the school's socio-economic position and teacher's experience wtih outdoor education ?The intervention will take place outdoors in a green-space (2 hours per week for 12 weeks) and include a toolkit of 30 activities to foster well-being (e.g. mindfulness) and academic competencies (e.g. mathematics). The control group will engage in teaching-as-usual and will be provided with the activity toolkit after the trial has been conducted. Questionnaires will be administered to students before, immediately after and 3 months after the intervention in both the control and intervention groups. Teachers in both groups will complete questionnaires before and immediately after the intervention.

Additional inclusion criteria for schools are: (a) access to a natural environment (e.g., park, wooden area) on school grounds or within 1 km of the school and (b) having 6th grade teachers provide informed and written consent to participate in this study. Inclusion criteria for children are (a) enrollment in 6th grade, (b) providing their assent and (c) having their parents or legal guardians provide informed written consent.