Historians collect and verify evidence and then interpret it in an acceptable way. A general consensus is that history does not present us with an absolute truth -- the most we can hope for is historians' reliable, evidentially based interpretations of the historical topic. History not viewed as interpretation has long raised alarm bells in history pedagogy circles. History educators are acutely aware that history taught as an uncontested body of positivistic knowledge with a canon of given factual information can promote prejudice, bias and bigotry -- it can ultimately fuel civil and international conflict and violence. Alternatively, history teaching as a constructivist process with multiple interpretations can be used to promote positive values -- history pedagogy can be a tool to support peace, reconciliation and conflict resolution. This places a major responsibility on a key objective of history teaching: addressing the concept of historical bias with effective methods of teaching on how to detect and analyse bias in historical sources for both primary and secondary schools. This paper reports an attempt at teaching secondary school students (aged 13 to 14 years) how to detect bias in primary written history sources while learning about a controversial topic in Maltese history -- church -- state relations in Malta in the 1960s. The method employed is qualitative research -- specifically pedagogical research -- which is research into the processes and practices of learning and teaching. In this case, the researcher tries new teaching methods with a small group of students, and their feedback regarding the exercise is examined. The students' ultimate answers after trying out the new scaffolding activities were quite encouraging, and show that breakdown of tasks is the key to helping understanding in history learning. The pedagogy employed is discussed in comparison to other approaches to teaching about bias. The paper also analyses student feedback on their learning about bias. Crucially, the paper addresses the impact of a specific intervention strategy to improve student understanding of, and ability to detect, bias in historical sources.