The Physics lesson on optics – or the behaviour of light as it passes through different materials – tends to be quick and easy. A simple experiment on refraction using a pencil and a glass of water elicits a small ripple of understanding, while breaking white light into its colourful constituents probably leaves a few minds open in wonder. But by the time children reach high school they have passed this stage of simple wonder and are just swotting for the exam, with the boards looming in the not too distant future.
Many chapters in the Physics textbook have an intimate connection with the tools and techniques of daily living, and optics is one of these. This science of light, or more correctly, the study of electromagnetic radiation, has three major branches – the study of the properties of electromagnetic radiation, both visible and invisible; the study of their manipulation through substances; and the effects and applications of the properties of light. The field, though, is divided into two main approaches to study – physical optics, which is concerned with the study of light and its effects, and geometric optics, which is concerned with the principles of the image forming properties of light. Whole industries are based on the science of optics, and optics makes many other industries possible. Often children lose interest in a subject because they cannot see its relevance to their lives. They do not really grasp the excitement of discovery and invention when all they see of the science is a few laws and rules. With optics, it is fairly simple to show these connections. When you begin the lesson on optics, try to give them a sense of the breadth of the science – but having done that, focus on one aspect. Lenses are a big part of applied optics that can be made interesting and relevant.