Design thinking and decision-making during the design process have been found to be hierarchical, representing a general pattern in which designers consider various types of intentions while conceptualising their particular design idea (Haupt, 2018; Vermaas, 2009). Hierarchical thinking can be observed through the investigation of thought development as evidenced in designers’ external representation strategies. The current CAPS document for the subject Engineering Graphics and Design seems to neglect the preliminary design phase of the design process and the connection with hierarchical thinking and idea transformation. As such, research is required to trace novice designers’ thinking processes and the transformation of their ideas. The purpose of this study is to explore and describe how novice designers’ hierarchical thinking processes support the transformation of ideas during preliminary design. In order to study the hierarchical thinking and idea transformation of designers, I adopted Extended Design Cognition and hierarchical thinking theories as the conceptual framework in this study. A mixed methods design was employed, embedded in a Critical Realist approach. Four third-year Industrial Design student participants from a local University of Technology in Gauteng were purposefully sampled. Verbal and visual data (sketches, 3D models, physical artefacts and gestures) were generated and documented by means of an in-vivo methodology and analysed qualitatively and quantitatively by means of ATLAS.ti. This study found that novice designers’ consideration of particular abstract aspectual intentions guided the way in which they generated and transformed their ideas. This study also found that they experienced a need to find a fit between their functional intentions and physical elements, allowing them to make both lateral and vertical transformations. This study contributes to the knowledge base on novice designers’ design cognition, specifically in terms of designers’ hierarchical thinking and idea transformation. To this end, this study provides pedagogical guidelines for current and future EGD teachers. / Dissertation (MEd)--University of Pretoria, 2019. / Science, Mathematics and Technology Education / MEd / Unrestricted