This special issue of "Canadian Social Studies" is dedicated to Roger I. Simon. Simon's scholarship bequeaths to theorists, teachers, and curators across Canada and beyond a theory of education that opens up responsibilities to past and present others. The papers gathered for this special issue address many of the difficulties that he dared educators to hold in mind. What Simon opens are big questions for education in a time more often consoled by the promise of solutions, best practices, and evaluation. These are questions about the interpretive quality of knowledge, the meaning of responsibility, justice, and the role of pedagogy in the reparation of historical trauma. Indeed, Simon lived with questions as the ground of his pedagogy, and in their articulation, he leaves behind an absence that is brimming with potential to make social and historical knowledge matter.