Higher-order reasoning, fundamental to ill-structured problem solving, was highlighted by many research studies that engaged learners in problem-centered learning activities. However, most studies did not clarify what higher-order reasoning skills are and how to scaffold them. On the other hand, important as problem solving is, few studies have been conducted to scaffold preservice teachers higher-order reasoning in solving technology integration problems. This dissertation focused on refining scaffolds to promote preservice teachers analytic, generative, and evaluative reasoning skills in planning technology-based lessons through iterative studies. Fixed scaffolds, provided as lesson design guides, were initially created based on propositions to support procedural, metacognitive, conceptual, and strategic scaffolding functions and directive and/or supportive mechanisms. Emerging evidence and theories were used to validate and extend the scaffolding propositions. Three journal-style manuscripts were included in this dissertation. The first paper delineates an overarching framework that defines higher-order reasoning skills during problem solving and presents ten tentative scaffolding propositions. The second paper is a design research study depicting three semester-long iterations during which scaffolds were designed, evaluated, and refined to support preservice teachers higher-order reasoning in an educational technology course. The first two iterations were qualitative studies involving four and two preservice teachers respectively. The third iteration was a mixed methods study, in which preservice teachers from four sections participated in the quantitative component and eight were selected for the qualitative component. The third paper contains a detailed description and evaluation of the fourth iteration, which used a two-stage scaffolding approach informed by previous iterations and the overarching framework. Again, the quantitative component included preservice teachers from four sections, and the qualitative component involved ten selected preservice teachers. Scaffolding strategies integrating multiple functions and mechanisms were refined. Finally, the dissertation concluded by comparing findings from the four iterations with the initial scaffolding propositions to discuss refined understandings and future research directions.