The importance of understanding what and how mathematics teachers notice is well documented, but more research is needed on content-specific noticing. In particular, knowing how teachers notice proportional reasoning, a vital topic spanning all grades of mathematics, could inform measures that support students’ proportional reasoning. We examined how teachers noticed when responding to two prompts (one student-focused and one teacher–student-interaction-focused) after watching a video of a middle grades proportional reasoning lesson. We analyzed the proportional reasoning reported from 13 elementary and 20 secondary prospective teachers and used cooccurrences along with noticing practices to describe how teachers noticed proportional reasoning and what aspects of proportional reasoning they noticed. Results indicate: (a) the two prompts resulted in differences in what and how participants noticed proportional reasoning, (b) participants were primarily descriptive and not interpretative when describing the proportional reasoning they noticed, and (c) the elementary and secondary prospective teachers both noticed similar aspects of proportional reasoning but showed differences in how the proportional reasoning cooccurred with the noticing practices. These findings reiterate the importance of the prompts used with teachers, the potential of using video to advance teachers’ noticing of proportional reasoning, and the methodological potential of using cooccurrences to examine teachers’ content-specific noticing.

了解数学教师注意什么以及如何注意的重要性已有充分记录，但需要对特定内容的注意进行更多研究。特别是，了解教师如何注意到比例推理这一涵盖所有数学年级的重要主题，可以为支持学生比例推理的措施提供信息。我们研究了教师在观看中年级比例推理课视频后对两个提示（一个以学生为中心，一个以师生互动为中心）做出反应时的注意情况。我们分析了 13 名小学和 20 名中学未来教师报告的比例推理，并使用共现和注意实践来描述教师如何注意到比例推理以及他们注意到比例推理的哪些方面。结果表明：（a）这两种提示导致参与者注意到比例推理的内容和方式存在差异，（b）参与者在描述他们注意到的比例推理时主要是描述性的而不是解释性的，（c）小学和中学的未来教师都注意到比例推理的相似方面，但在比例推理如何与注意实践同时发生方面表现出差异。这些发现重申了教师使用提示的重要性、使用视频来提高教师对比例推理的注意的潜力，以及使用共现来检查教师对特定内容的注意的方法论潜力。