The school subject Mathematical Literacy requires application of mathematics procedures in various contextual settings, but not much is known about the ways in which students engage with contextual settings such as inflation. This qualitative study was conducted with in-service Mathematical Literacy teachers in South Africa with the purpose of exploring the extent to which the teachers recognised the contextual constraints involved in applying the percentage change calculation to the inflation context. The written responses of the 406 Mathematical Literacy teachers were scrutinised to identify their interpretations of the contextual constraints involved in applying the percentage change procedure to the context of inflation. The item required the application of two successive percentage change operations (corresponding to the inflation rates for the 2 years). Of the 406 responses that were analysed, 260 (65%) were unable to take account of all the contextual constraints. There were 108 teachers who reduced the procedure to a one-step calculation while 64 teachers interpreted the context as a percentage decrease scenario. A large number of teachers (162) struggled with the interpretation of the role of the year, k , in the relationship between the quantities. The findings indicate that engagement with and understanding of the concept of inflation is dependent on a synthesis of the contextual constraints into the mathematical procedures. This article provides some insights into the struggles with making sense of the contextual nature of inflation which is an area that has received little attention in mathematics education studies. The teachers’ struggles likely mirror learners’ struggles and hence the research applies in a similar way to learners.

中文翻译：

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百分比变化计算在数学素养通货膨胀背景下的应用

学校课程“数学素养”要求在各种情境中应用数学程序，但是对于学生如何适应诸如通货膨胀之类的情境环境知之甚少。这项定性研究是与南非在职的数学素养教师进行的，目的是探索教师认识到在将百分比变化计算应用于通货膨胀背景时所涉及的背景限制的程度。仔细审查了406位数学素养教师的书面回答，以确定他们对将百分比更改程序应用于通货膨胀环境时所涉及的环境约束的解释。该项目需要应用两个连续的百分比更改操作（对应于两年的通货膨胀率）。在分析的406个回复中，有260个（65％）无法考虑所有上下文限制。有108位教师将程序简化为一步计算，而64位教师则将上下文解释为百分比减少方案。大量的教师（162）难以解释年份k在数量之间的关系中的作用。研究结果表明，对通货膨胀概念的参与和理解取决于将上下文约束综合到数学程序中。本文提供了一些有关通货膨胀的背景知识的见解，而通货膨胀的上下文本质在数学教育研究中很少受到关注。教师的挣扎很可能反映了学习者的挣扎，因此该研究以类似的方式适用于学习者。