<p>Collaborative argumentation offers rich opportunities for sensemaking, yet its cognitive and epistemic demands can overwhelm students, especially when confronting the inherent uncertainty of socioscientific issues (SSIs). To address such challenges, this quasi-experimental study integrated explicit scripting with scientific uncertainty navigation to scaffold collaborative argumentation and investigated how it may influence fifth-grade students’ conceptual understanding, critical thinking, and learning engagement with SSIs. A total of 73 students from two intact classes at a rural primary school in China were assigned to either an experimental group (n = 37) or a control group (n = 36). Over eight weeks, both groups engaged in two SSI units, food safety and global climate change, but only the experimental group received a stepwise collaboration script emphasizing identification, maintenance, and resolution of uncertainty, whereas the control group participated in unscripted argumentation. Quantitative data were collected through pre- and post-tests assessing conceptual knowledge, critical thinking dispositions, and dispositions toward uncertainty navigation. ANCOVA results revealed that, after the first SSI unit, no significant differences were observed except for conceptual understanding, but the experimental group significantly outperformed the control group on all outcome measures after the second unit. Qualitative interviews corroborated these findings,&#xa0;revealing a growing appreciation for uncertainty and improved collaboration as a result of scripting. The current findings indicate that scripting collaborative argumentation with explicit uncertainty navigation can foster deeper content learning, critical thinking, and engagement, particularly when students become accustomed to its norms over time, which offers important implications for future design of argumentation-based science instruction.</p>