An essential aspect of scientific practice involves grappling with the generation of predictions, representations, interpretations, investigations, and communications related to scientific phenomena, all of which are inherently permeated with uncertainty. Transferring this practice from expert settings to the classroom is invaluable yet challenging. Teachers often perceive struggles as incidental, negative, and uncomfortable, assuming they stem from students' deficiencies in knowledge or understanding, which they feel compelled to promptly address to progress. While some empirical research has explored the role of scientific uncertainties in driving productive student struggle, few studies have explicitly examined or provided a framework to unpack scientific uncertainty as it manifests in the classroom, including the sources that lead to student struggle and how teachers can manage it effectively. In this position paper, we elucidate the importance of incorporating scientific uncertainties as pedagogical resources to foster student struggles through uncertainty from three perspectives: scientific literacy, student agency, and coherent trajectories of sensemaking. To develop a theoretical framework, we consider scientific uncertainty as a resource for productive struggle in the sensemaking process. We delve into two types (e.g., conceptual, epistemic), four sources (e.g., insufficiency, ambiguity, incoherence, conflict), and three desirability considerations (e.g., relevance, timing, complexity) of scientific uncertainties in student struggles to provide a theoretical foundation for understanding what students struggle with, why they struggle, and how scientific uncertainties can be effectively managed by teachers. With this framework, researchers and teachers can examine the (mis)alignments between uncertainty-in-design, uncertainty-in-practice, and uncertainty-in-reflection.