Instructional explanations are sometimes viewed as part of a nonconstructivist, solely teacher-centered learning environment, leading to the perception that they are ineffective or inappropriate for teaching science. Consequently, teacher education programmes seldom focus on preparing teachers to explain scientific concepts effectively. Interestingly, the perception of a specific kind of instructional explanation in teaching has evolved in recent years: explanatory videos, in particular, are being viewed as promising digital tools for learning. This article asserts that instructional explanations constitute integral components within nearly all learning environments where communication about science takes place. It has two goals. Firstly, the article aims to develop a coherent, constructivist theory of explaining, including both teacher explanations and explanatory videos. This theory offers an inductive-statistical explanation of the underlying mechanisms of communicative situations that involve experts and novices. Secondly, based on this constructivist perspective, the article distinguishes instructional explanations from scientific explanations and argumentation. It contends that (a) reducing instructional explanations solely to teacher-centered, didactic teaching represents a misconception with potentially adverse effects and (b) it also is a misconception that instructional explanations, scientific explanations, and argumentation are (nearly) interchangeable. The paper argues that instructional explanations, including both teacher explanations and explanatory videos, are not only a potentially effective part of all kinds of science teaching but also a core practice of science teachers.