Shedding light on boundaries: re-sequencing Snell’s law instruction to first build conceptual understanding

Abstract

Abstract Refraction is a foundational concept within introductory physics. Physics students need a deep understanding of refraction, including Snell’s Law, in order to progress towards more complex optics topics such as lenses and images. Unfortunately, many physics students obtain only a superficial understanding of refraction. Although many students can use Snell’s Law to perform basic calculations, the mathematical relationship is often divorced from students’ conceptual knowledge, which often harbours misconceptions. In this article, we describe a sequence of instructional activities that we have used in an introductory optics course that aims to address common issues of students’ learning of optics. Instead of leading with Snell’s Law and emphasising calculations, the instructional sequence places conceptual understanding in the foreground. Mathematical representations are introduced only after students have developed a conceptual foundation; in this way, mathematics becomes integrated with students’ conceptual understanding rather than existing apart from it. After describing the instructional sequence, we present the impacts of instruction on student thinking and also suggest potential applications of the instructional principles that guided our decision-making.