In this research, we have explored the possible differences in students' performance in grade nine chemistry exams that could have been influenced by a different instructional approach in grade eight. We compared two groups of students: one group had received a transmissive propaedeutic approach in grade eight (especially related to the memorising the Periodic Table and mastering the rules of chemical nomenclature), and another group had received competence-based instruction in grade eight (more emphasis on modelling and inquiry activities). Both groups were homogeneously mixed at the end of grade eight, and they both received a transmissive approach in grade nine. Data were gathered through four exams over grade nine in both groups, and final course grades were also retrieved and compared. We found significant differences in assessment scores between both groups at the beginning of grade nine, but those differences were not found in subsequent assessments and in students' final grades. Therefore, our results would suggest a scarce effect of the instruction of formal and propaedeutic content in grade eight, as all students could reach the same level regardless of the instruction received in the previous year.