The purpose of this study was to investigate the nature of students' responses to a cross-cultural science unit entitled "Maintaining health." The unit was designed to help students to build bridges between their traditional practices and beliefs and western science concepts. This paper reports students' responses to a pre-test and post-test, and their reflections on their learning. The responses were analysed using the collateral learning model. There was evidence of parallel, dependent, and secured collateral learning. The implications for science teaching and for assessing science learning are discussed.