Introductory physics is taught to several hundred thousand university students every year. It is seen as especially difficult by many and the failure rate is often high. A relevant question is whether one can increase the success rate among the weaker students? Retrieval practice is an established learning strategy with large benefits. However, as pointed out last year in this journal, hardly any systematic research has been done on retrieval practice in physics. Here we present a novel tool for retrieval practice in physics called the hierarchical principle structure for mechanics (HPSM). HPSM hierarchically organizes the essential principles, equations, and definitions for translational, rotational, and fluid mechanics, to emphasize meaningful connections. We investigated HPSM in a two-phase study. First, we present a randomized controlled experiment showing that 70 min of retrieval practice of HPSM had a very large effect on a declarative factual test compared to 70 min of problem study, $d=1.42$. In the second phase, which was carried out the following year, we implemented distributed retrieval practice of HPSM in the first 15 min of 16 lectures. Although difficult to disentangle the effect from the lectures it was embedded in, distributed retrieval practice of HPSM seems to promote factual knowledge ($r=0.44$) and better exam results for the weaker students (significant main and interaction effects).

中文翻译：

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大学入门物理学中分级原理结构的检索实践：培养更强的学生

每年向数十万大学生讲授入门物理学。许多人认为这特别困难，并且故障率通常很高。一个相关的问题是，是否可以提高弱势学生的成功率？检索练习是一项既有好处的既定学习策略。但是，正如去年在该杂志中指出的那样，几乎没有对物理学中的检索实践进行任何系统的研究。在这里，我们介绍了一种用于物理学中的检索实践的新颖工具，称为力学的层次原理结构（HPSM）。HPSM分层次地组织了平移，旋转和流体力学的基本原理，方程式和定义，以强调有意义的连接。我们在两阶段研究中调查了HPSM。第一，$d=1.42$。在第二年（第二年进行）中，我们在16堂课的前15分钟内实施了HPSM的分布式检索实践。尽管很难将其效果与所嵌入的演讲相区分，但是HPSM的分布式检索实践似乎可以促进事实知识的发展（$\mathrm{[R}=\mathrm{0。}44$），并为较弱的学生提供更好的考试成绩（主要的互动效果）。