Using an in-depth case study approach, this study explored the mathematics educational values held by two in-service teachers at the primary and secondary levels in Hong Kong through lesson observations and deep structured interviews. The findings revealed that the primary teacher emphasized fun, flexibility, critical thinking, and coherence, while the secondary teacher prioritized achievement, control, higher-order thinking, and progression. Using Seah and Bishop's five complementary pairs framework, the primary teacher aligned with an activist, relational, relevance, and accessibility perspective, contrasting sharply with the secondary teacher. This reflected a shift in values in response to students’ educational stages, revealing the challenges of balancing social expectations and nurturing future science, technology, engineering, and mathematics talent. We discussed the implications for local education reforms, including modernizing assessment methods and curricula, reshaping the social climate, and updating professional development to address these tensions. Copyright © 2024 The Author(s).