This study will test the effectiveness of a brief educational intervention that teaches youth that they can grow and change, known as "growth mindset." Similar growth mindset interventions have improved youths' well-being and academic skills, and reduced risk for depression. In this study, youths' depressive symptoms and well-being will be measured before the intervention and then again 4 months after the intervention to determine if the intervention had a positive impact for youth experiencing transitions (firs and last years of high school).

Adolescents experience many major life transitions during high school, including changes in educational settings, living arrangements, and social and romantic relationships. While these transitions may be experienced as positive new beginnings for some youth, others experience them as stressful and challenging. Further, the developmental period of adolescence is characterized by an increased risk for the development of mental illnesses such as depression. In the context of widely-accepted cognitive models of adolescent depression, adolescents with pre-existing vulnerabilities for depression (e.g., negative self beliefs) may be more prone to experience certain life transitions as especially stressful, and this vulnerability/environment combination is likely to bring about depressive symptomatology for vulnerable youth. Thus, there is a pressing need to better understand factors that not only protect youth from mental illness during transitions, but also factors that promote resilience and well-being. Indeed, high schools are eager to address student mental illness and find better ways of promoting mental health and well-being in schools.

This project employs clinical, cognitive, developmental, and positive psychology theories in an attempt to better understand factors that may be important for adolescent mental illness and mental health during this important time of transition. Specifically, we aim to examine the utility of a brief online educational intervention for promoting adolescent mental health during important life transitions.

One important factor that appears to be associated with wellbeing and resilience is that of beliefs about growth and response to failure. Individuals often respond to challenge by either a) retreating and/or making negative attributions about themselves or others, or b) view challenge as an opportunity for learning and growth, and not consider failure to be an indication of personal shortcomings. The difference between these two responses to challenge reflects beliefs about the malleability of personal characteristics; these beliefs are referred to as "implicit theories" or more colloquially "mindset". Those who hold "entity" theories (fixed mindset) believe personal characteristics are stable and unchanging, while those with a malleable or "incremental theories" (growth mindset) believe personal characteristics are changeable and can be developed through effort and learning . Research has broadly suggested that those with entity theories may be more prone to experience difficulties and be at risk for mental illness, while those with incremental theories experience greater resilience and well-being.

Previous research has indicated that incremental theory can be taught via educational interventions, and increasing belief in incremental theory has been associated with positive effects. Further, integrating positive psychology into educational institutions to foster youth development has been recommended by many researchers. Youth spend substantial amounts of time in school, making schools an appropriate setting for interventions that aim to promote well-being and prevent mental illness. Thus, this study will test the effects of a brief implicit theory intervention on well-being and depressive symptoms.The intervention is similar to previous implicit theory interventions and teaches youth an incremental theory of socially relevant characteristics (i.e., that people can change and that personal attributes are malleable).

Implicit theory of personality (ie, beliefs about the malleability of personal attributes and socially relevant characteristics) has also been associated with depressive symptoms in youth. In a study of grade 9 students, researchers found that a brief intervention that taught incremental theory of personality (that personal attributes can grow and change) was associated with stability of reported levels of depressive symptoms over 9 months. In this intervention, students read a compelling article that demonstrated incremental theory of either personality (experimental) or athletic ability (control), then students were asked to summarize the lesson of the article and apply their own experience. Over time (9 months) those in the control condition showed an increase in depressive symptoms while those exposed to the incremental theory of personality did not show the same increase, and incidence of clinically significant depressive symptoms remained stable. The increase seen in the control group was noted to be proportional to that commonly experienced by those transitioning to high school, suggesting the intervention may have promise for successfully ameliorating developmentally typical increases in depressive symptoms. Although this brief intervention was associated with significant positive outcomes, replication and application to other samples at risk for depressive symptoms (such as youth transitioning out of high school and to post secondary education) is warranted. Towards this end, the current study will examine the impact of an intervention that teaches incremental theory on well-being and depressive symptoms in students in the first and last years of high school.

Inclusion Criteria:

• A student at one of the recruited schools in grade 9 or 12
• Age 13-18 years
• Able to read and write fluently in English
• Have parent/guardian consent, and provide participant consent

Exclusion Criteria:

• Not a registered student at one of the recruited schools
• Less than 13 or more than 18 years old
• Unable to read and write fluently in English
• Does not have parent/guardian consent or does not consent to participate

There is no plan to share individual participant data as this has not been approved by our Research Ethics Board

Participants will not be informed that there are different versions of the educational program and thus will be blind to group allocation. Randomization will be fully automated by the online intervention administration system such that researchers will also be blind to group allocation during intervention administration as well as during pre- and post-intervention data collection. Because randomization is automated, neither researchers nor participants will be able to predict randomization assignments. Outcomes will be measured quantitatively thus no assessment of primary outcomes will take place. However, assessors of the manipulation check (which codes for participant engagement in the intervention) will not be masked and thus will be aware of allocation (experimental or control).