Meaningful Contrasts - Investigating the Potential of Scaffolded Contrasting Cases to Promote Students’ Mechanistic Reasoning in Organic Chemistry

在过去的十年里，人们普遍认识到，在高等教育阶段，对学生的有机化学期望与学生实际表现之间存在很大差异。学生在处理有机反应机理时的表面焦点阻碍了对不同有机化学表征的适当解释和化学概念的使用。研究表明，成功的机械推理取决于学习者的能力，连接结构特征的潜在的内隐属性，并在一个过程中，而不是一个面向产品的方式接近反应的变化。以往的研究表明，比较机械推理遵循一个基本的推理结构，可以用来指导学生解决有目的地设计的对比案例，但支架学生解决对比案例时的解释作为一种潜在的手段，以提高机械推理能力的有机化学尚未进行定量研究。为了满足记录在案的需求，我们的目标是描述1）。任务格式的效果，即与传统单一情况相比的对比情况，以及2.）外显支架对学生机械推理的影响。在这项研究中获得的见解提供了宝贵的启示，如何支持学生在推理有机化学反应过程。

In the last decade, it has largely been recognized that there is a big discrepancy between what is expected of students in organic chemistry at the tertiary level and what students actually show. Students’ surface focus when dealing with organic reaction mechanisms hinders the appropriate interpretation of different organic chemical representations and the use of chemical concepts. Studies show that successful mechanistic reasoning depends on the learner's ability to link structural features to the underlying implicit properties and to approach change of a reaction in a process-, instead of a product-oriented manner. We could show in previous studies that comparative mechanistic reasoning follows a basic reasoning structure that can be used to guide students in solving purposefully designed contrasting cases.However, scaffolding students’ explanations when solving contrasting cases as a potential mean to enhance mechanistic reasoning abilities in organic chemistry have not yet been under investigation quantitatively. In order to close the documented need, we aim at characterizing 1.) the effect of the task format, i.e. contrasting cases compared to traditional single cases, and 2.) the effect on an explicit scaffold on students’ mechanistic reasoning. The insight gained in this study provides valuable implications on how to support students in reasoning about reaction processes in organic chemistry.