To cultivate the capability of making informed decisions on socioscientific issues, ideally, we hope students would engage in discerning and evaluating justifications for and against different positions while constructing well-structured, persuasive arguments. When argumentations do not develop ideally, it is important to understand the constraints presented. This study explores a case where socioscientific argumentation (SSA) in a fifth-grade classroom showed unbalanced structural and content quality. The students' oral arguments and post-discussion written arguments both demonstrated quality structure in terms of justification use, multiple perspective-taking, and rebuttals, and low accuracy level of knowledge-based justifications. Tracing the development of the SSA, we identified a few teaching and learning features that shaped this discourse pattern, including an overemphasis on structure, side-taking setting, context knowledge provided in brief points, and the students' lack of content and context knowledge. Implications for practice and future research were discussed in reflection.