The introduction of 'differentiated' instruction (DI), tailored to meet students' individual needs, has influenced educational policies throughout the world, including Hong Kong. Recent studies indicate that school-university partnerships (SUP) for pre-service teacher education (particularly during practicum) can foster DI practice but research exploring the impact during in-service teacher education remains limited. This phenomenological study addressed that gap by using arts-based methods, focus group interviews, and thematic analysis to provide clear structure for generating rich understandings of in-service teachers' perceptions. Likening the process of implementing DI to a rainforest with diverse species, where crocodiles (i.e. teachers) of different sizes can both 'swim and walk' to manage the dynamic challenges and complexities, teachers identified four key factors: (1) external advice; (2) teacher collaboration; (3) teacher commitment; and (4) integration into school policy.