The transition from high school to post-secondary STEM studies presents significant challenges for many students. The multidisciplinary nature of STEM careers and the discrepancy between the knowledge-based high school approach and the experiential undergraduate model often leads to disillusionment. While early exposure to STEM disciplines is crucial, the subject-specific nature of many US high school programs contrasts with the broader approach in the Ontario system, where subject specialization occurs later. Even with innate interest, success in later, non-mandatory STEM courses hinges on prior achievement, potentially hindering engagement. Specialized STEM high schools offer a solution through advanced coursework and research opportunities, promoting critical thinking and problem-solving. However, these schools are not universally accessible. Post-secondary led programs offer an alternative, but field trips alone fall short of providing the immersive experience needed for long-term impact. Longer-term immersive programs, including after-school and summer programs, have proven successful in fostering self-determination and inquiry-based learning. Such programs often incorporate hands-on experience, self-motivated learning, real-world application, immediate feedback, and problem-based projects. In response, the University of Toronto graduate trainees created *Discovery*, a term-long inquiry-focused program designed for senior high school students in non-specialized schools. Partnering with George Harvey Collegiate Institute, *Discovery* uses biomedical engineering as a context, leveraging university facilities and teachers to create a relevant learning community and foster critical thinking skills. This program aims to bridge the gap between high school knowledge-based learning and post-secondary experiential learning by engaging students in challenging, real-world biomedical engineering projects.

The literature emphasizes the importance of early STEM engagement and highlights the challenges students face transitioning to post-secondary studies. Studies in the US have focused on subject-specific STEM courses, while the Ontario system offers a broader approach initially, leading to specialization in later grades. The literature also examines the effectiveness of various STEM interventions, including specialized schools, field trips, after-school programs, and summer camps. Specialized STEM schools are shown to be highly effective in cultivating STEM engagement, but accessibility is a major limitation. The literature supports the notion that longer-term immersive research experiences, hands-on activities, self-motivated learning, real-life application, immediate feedback, and problem-based projects are vital for fostering self-determination and long-term STEM interest. The importance of positive student attitudes and the role of learning communities in enhancing motivation and persistence are also highlighted. The need to create exciting and relevant curricula is underscored as fundamental to sustaining STEM engagement among high school students.

The *Discovery* program was implemented over five academic terms, involving collaboration between the University of Toronto's Institute of Biomedical Engineering and George Harvey Collegiate Institute. Each term, senior high school students (Grades 11 and 12) participated in a project-based learning experience based on a central biomedical engineering (BME) global research topic. Students worked in teams (3-4 students) within their class cohorts, guided by U of T trainees and their high school teachers. Experiments were conducted in U of T teaching facilities, with students introduced to relevant techniques and safety procedures. The program used a problem-based engineering capstone framework, involving iterative project development and refinement based on feedback. Student assessment encompassed several deliverables: introductory essay, client meeting, proposal, progress report, poster, and final presentation. The final product was a research poster presented at a symposium. Over five terms, 268 instances of student participation were tracked, representing 170 individual students, with some students participating in multiple terms. Pre- and post-term surveys assessed program effects on STEM interest and engagement. High school teachers assessed all deliverables using consistent rubrics. Two student cohorts were identified for analysis: "Exceeds Expectations" (EE) students (achieving ≥1 SD grade differential in Discovery over their final course grade) and "Multiple Term" (MT) students (participating in Discovery more than once). Data analysis included paired t-tests, linear regression, Mann-Whitney U-tests, and analysis of attendance data. Surveys explored student perceptions of academic challenge, comfort in university lab environments, impact on STEM pursuit, and willingness to participate again. The program was later expanded to a second school with a nominally higher Learning Opportunities Index (LOI), which allowed for comparison across varying socioeconomic backgrounds.

Students participating in the *Discovery* program achieved significantly higher cumulative Discovery grades than their cumulative classroom grades (p < 0.0001). A significant correlation (p < 0.0001) existed between the Discovery grade and the final course grade, indicating that success in the inquiry-based program translated to improved overall performance. Analysis of two subgroups revealed significant findings: 1. **Exceeds Expectations (EE) Students:** This group, defined as students with a ≥1 SD (18%) grade differential between Discovery and final course grade, showed lower course grades (p < 0.0001) but significantly higher final Discovery grades (p = 0.0004). They significantly outperformed non-EE students in most Discovery deliverables. There was no significant difference in classroom attendance between EE and non-EE students. 2. **Multiple Term (MT) Students:** MT students, participating more than once, did not have significantly higher course grades than single-term students, but achieved significantly higher final Discovery grades (p = 0.0067). MT students demonstrated a significant increase in Discovery grades over time (p = 0.0011) and performed significantly better on the progress report (p = 0.0021). Longitudinal assessment showed a significant trend of improved performance across multiple deliverables. MT students also missed significantly less class time (p = 0.010) than single-term students. Attendance data showed excellent Discovery attendance (at least 91% of participants attended all sessions), contrasting with wider class attendance distribution. Qualitative observations from teachers highlighted students' prioritization of *Discovery* assignments and renewed perceptions of student potential. Student surveys showed that at least 91% felt the program was sufficiently challenging, 94.6% felt more comfortable working in university lab environments, 72.4% felt more likely to pursue STEM interests, and 84.9% expressed interest in future participation. Expansion to a second school with higher LOI (lower SES) yielded similar results, demonstrating the program's impact across varying socioeconomic contexts.

The findings demonstrate the value of inquiry-based learning environments for students who struggle in traditional, knowledge-focused classrooms. The significant performance gains in the *Discovery* program, especially among the EE students, suggest that a hands-on, project-based approach can significantly improve academic outcomes. The high attendance rates and positive student perceptions highlight the program's engagement potential. The success of the MT students underscores the benefits of repeated exposure to this type of learning. The program's impact across varying socioeconomic backgrounds suggests its scalability and generalizability. While the study focuses on short-term effects, the findings suggest significant potential for long-term impact on student STEM engagement and career choices. The results support the notion that creating relevant learning communities and fostering critical thinking skills are crucial for enhancing student performance and interest in STEM.

The *Discovery* program offers a successful and scalable model for inquiry-based STEM education in secondary schools. The program significantly enhanced student performance, engagement, and positive attitudes toward STEM, particularly among underperforming and repeat participants. Future longitudinal studies are needed to assess long-term impacts on students' educational trajectories and career choices. Expansion to other disciplines and further investigation into the program's mechanisms for success are recommended.

The study's scope was limited to a specific set of high schools and students over a relatively short timeframe. The data relies on teacher assessment and student self-reporting, which might introduce bias. The limited number of high schools included in the study and the limited longitudinal follow-up may limit the generalizability of the findings. Further studies are needed to assess the long-term effects of the program and determine its effectiveness across a more diverse range of school contexts and student populations.