Professional experience during initial teacher education (ITE) influences the pedagogical approach of beginning secondary mathematics teachers but often restricts them to a limited set of teaching methods. This study investigates the impact of a co-curricular program on the pedagogical development of Secondary Mathematics Education preservice teachers (Secondary PSTs). In the program, Secondary PSTs taught foundational mathematics to Primary PSTs in the Bachelor of Primary Education. Data were collected from semi-structured focus group interviews conducted annually from 2021 to 2023. Participants highlighted the contrast between traditional high school placements and the reform-oriented teaching practices in the program. They valued the flexibility and creativity allowed in the Foundations classes but noted challenges in explaining concepts without tutor support. The program also prompted Secondary PSTs to deepen their content knowledge to effectively address Primary PSTs’ misconceptions. Overall, the study suggests that near-peer teaching experiences can enhance Secondary PSTs’ pedagogical and content knowledge, offering valuable insights for improving ITE programs.