The relationship between knowledge and literacy is a central concern for all teachers. In his teaching, Palek noted that his students were struggling to understand complex substantive concepts such as "parliament" and decided to explore the relationship between students' understanding of a concept and their wider substantive knowledge that rendered the concept meaningful. Through a careful analysis of students work, Palek concluded that there is a close relationship between a student's ability to construct a causal argument and his or her "security" in understanding relevant substantive concepts. Such a conclusion further supports a renewed emphasis by history teachers on the role played by substantive knowledge in the process of learning history as a discipline, and raises questions about the means by which pupils' progression in history might be assessed.