Abstract
The present study evaluates the effect of a specialized long-term enrichment program in chemistry, implemented as extracurricular courses at the Sofia Mathematics High School, on the performance of gifted students (Grades 8 – 11) across the three stages of the National Chemistry Olympiad (NCO). A quasi-experimental study was conducted with 214 students from two cohorts, with the intervention for each cohort spanning three consecutive academic years. The results indicate significantly stronger performance by the experimental groups (EG) compared to the control groups (CG). Students participating in the program achieved higher qualification rates at the municipal level (81% vs. 10%) and the regional level (41% vs. 0%). Only students from the experimental groups advanced to the national stage, where 67% ranked in the “Top 10” and secured 15 out of a possible 18 medals. The findings confirm that the enrichment program has a positive effect on student performance at all stages of the National Chemistry Olympiad and proves decisive for success at the more demanding competition levels.