The measurement of magnitudes was at the foundation of numbers and calculation in academic mathematics until the 19th century. It provided units and the concrete and abstract numbers that formed the basis of school arithmetic up to the mid-20th century in France. Our analysis of changes in teaching resources for proportionality (late 19th to the early 21st century) documents how the disappearance of magnitudes in academic knowledge was followed by the loss of the differentiation of the conceptual complexity of mathematical ideas related to proportionality. These changes made teaching and learning about proportionality considerably more difficult, and we later witness their gradual, but not yet systematic, reversal.

直到 19 世纪，量级的测量一直是学术数学中数字和计算的基础。它提供了单位以及构成直到 20 世纪中叶法国学校算术基础的具体和抽象数字。我们对比例性教学资源变化的分析（19 世纪末至 21 世纪初）记录了学术知识量级的消失如何导致与比例性相关的数学思想的概念复杂性的差异性丧失。这些变化使相称性的教学和学习变得更加困难，我们后来见证了它们逐渐但尚未系统化的逆转。