This paper explores ways in which data collected during designerly activity in a Secondary Design and Technology Classroom in the UK, can be analysed with a view to ascertaining the features of the classroom interactions which facilitate the development of designerly activity in "fledgling designers" (Trebell, 2007). The paper builds upon earlier work (Trebell, 2007, Trebell 2008) including a pilot study (Barlex and Trebell, 2007). One research question drove this of study: "What are the features of the classroom interactions that support pupil's design activity?" This paper presents, analyses and discusses the video data collected throughout the duration of a design-without-make assignment. The data was analysed against three analytical categories drawn from the literature. These consist of: (a) "Design decisions" (Barlex, 2005), (b) "Learning conversations" (Corden 2001; Coultas, 2007; Hamilton, 2003; Kumpulainen & Wray 2002; Wegeriff and Mercer 2000) and (c) "Scaffolding and Mediation" (Schaffer, 1996; Tharp and Gallimore, 1988) supplemented by a range of "emergent categories" drawn from the data. Findings indicate that the features of the classroom interactions which support the development of designerly activity in fledgling designers are complex, multi-facetted and either enabled or disabled by the pedagogic stance adopted by the teacher. (Contains 4 tables and 4 figures.)