School tracking and measurement of educational outcomes Notes: This figure illustrates the structure of the school system in the canton of Zurich. Children attend primary school for six years from ages 7 to 12 (Grade 1 to Grade 6). At the end of primary school, at age 12, children are tracked either into academic high school (Gymnasium) or into regular high school (Sekundarschule). The tracking outcome is determined exclusively by children's grades in the final year of primary school and academic high school admission test scores. Children can either attend an academic high school directly starting from Grade 7 (long-term Gymnasium) or from Grade 9 onward (short-term Gymnasium). The non-academic high school track comprises three lower tracks called Sek A, Sek B, and Sek C. Children attending regular high school can also transfer to academic high school after two or three years. The Matura degree, obtained upon completion of academic high school, is required to enrol in university. Students graduating from regular high school typically start an apprenticeship at age 16. Apprenticeships last two to four years. The red vertical bar indicates the intervention period. The yellow bars indicate the points in time when we observe educational outcomes.