Instructors manage several tensions as they support students to engage in mathematical disciplinary practices such as defining, conjecturing, and proving. These tensions include honoring students' contributions while simultaneously apprenticing students to following mathematical norms. I present a case study of a teacher-researcher in a laboratory setting who was particularly skilled at this endeavor. I found that the teacher-researcher engaged in a pattern in which the teacher-researcher cycled between inquiring into the students' thinking about their draft of a definition, conjecture, or proof and then engaged in scaffolding, including scaffolding of mathematical norms. I exemplify this pattern with an episode of students writing a conjecture equivalent to the Archimedean Property that served as a warrant for one of their proofs. I close the paper discussing complexities of apprenticeship into the norms of the discipline. [For the complete proceedings, see ED657822.]