Large language models (LLMs) are promising tools for scaffolding students' English writing skills, but their effectiveness in real-time K-12 classrooms remains underexplored. Addressing this gap, our study examines the benefits and limitations of using LLMs as real-time learning support, considering how classroom constraints, such as diverse proficiency levels and limited time, affect their effectiveness. We conducted a deployment study with 157 eighth-grade students in a South Korean middle school English class over six weeks. Our findings reveal that while scaffolding improved students' ability to compose grammatically correct sentences, this step-by-step approach demotivated lower-proficiency students and increased their system reliance. We also observed challenges to classroom dynamics, where extroverted students often dominated the teacher's attention, and the system's assistance made it difficult for teachers to identify struggling students. Based on these findings, we discuss design guidelines for integrating LLMs into real-time writing classes as inclusive educational tools.

翻译：大型语言模型（LLMs）作为提升学生英语写作能力的辅助工具具有广阔前景，但其在实时K-12课堂中的有效性仍未得到充分探索。为填补这一研究空白，本研究考察了将LLMs作为实时学习支持工具的益处与局限，重点关注课堂约束条件（如学生能力水平差异与时间限制）如何影响其效果。我们在韩国一所中学的英语课堂中开展了为期六周的实证研究，共有157名八年级学生参与。研究发现：虽然分步引导的脚手架方法提升了学生构建语法正确句子的能力，但这种方式降低了低水平学生的学习动机，并增强了他们对系统的依赖性。同时，我们观察到课堂动态面临的挑战——外向型学生往往占据教师更多关注，而系统的辅助使得教师难以准确识别学习困难的学生。基于这些发现，我们探讨了将LLMs作为包容性教育工具整合到实时写作课堂中的设计准则。