Optical fibre communication enables the global internet, but few youths ever learn about how it works, even at a basic level, until tertiary education. While some middle school curricula might include simple geometrical optics concepts like reflection and refraction, they often lack contextual linkage to worldwide telecommunications. Through our studies, we have found that students are more engaged in the learning process when the material directly relates to real life. To address this gap, and moreover to tackle the issue of the STEM skills shortage, we have designed a self-contained lesson to introduce youths to this topic. It is modularised into three parts, beginning with using light to communicate Morse code, and then covering advanced themes such as multiplexing and fibre guidance based on total internal reflection. The modules can be taught sequentially or individually depending on educational level. They emphasise a more phenomenological than theoretical approach and include hands-on activities using easily obtainable materials. We outline the lesson and pedagogical guidelines for classroom settings, as well as evaluate actual classes run. This lesson can be flexibly implemented in formal classes or through educational outreach programmes.