In this paper, we presented and discussed our implementation path of the design-based research toward fostering collaborative knowledge building culture in the context of teaching and learning integrated humanities in a Singapore secondary school. Specifically, we focused on the design and enactment of two mobile learning trails and related activities in and out of school contexts that aim to scaffold students toward explicit idea sharing and productive discussion in authentic learning contexts. The design of the first mobile learning trail served as a platform to acquaint students with collaborative learning in situ: idea generation and improvement. In the second learning trail, we provided more scaffolding to help students engage in intentional, continuous and pervasive knowledge building discourse and activities. Data sources included online surveys, focus group interviews, and teacher’s anecdotal reflections. Overall, we found that students appreciate opportunities for collaborative mobile learning in situ leveraging on the affordances of the physical environment and mobile technologies. However, we also found that while students hold positive perspectives toward collaborative knowledge building, their actual mode of learning is more cooperative than collaborative, indicating some conflicts between their espoused beliefs and beliefs in action. In conclusion, we argued that promoting a culture of collaborative knowledge building amongst Singapore students requires the “careful orchestration” of lesson design, lesson implementation and appropriation of relevant devices and applications.