The study explored the origins of students' data handling knowledge and skills employed during secondary Science lessons. Transfer of learning was explored in an authentic school context, describing when transfer does and does not occur, conditions that appear to foster transfer, and impacts of different types of transfer on teaching and learning. The data sets collected through case study methods consisted of 13 units of Science lesson observations and interviews with 60 students and 11 teachers over the course of one academic year. Students' claims of where, when, and how they acquired data handling knowledge and skills were described and analyzed to determine whether transfer occurred or new teaching was required. The findings strongly suggest that transfer does occur among secondary school classrooms, having both positive and negative outcomes for learning and performance. Thus, educators and researchers need to rethink expectations about and implications of this transfer.