Video narration
What changes when you switch on a torch in a dark room? Before the switch, the objects are still there, but little light from them reaches your eyes. The beam leaves the torch and travels through the room. Light is energy moving from a source; brightness is what you notice when that energy reaches you. Some light travels straight into your eyes. When it hits a book or wall, it can bounce off: that is reflection. Light reflected from the object reaches your eyes, and you see it. Light can also change direction as it passes between materials, such as air and water. That is refraction, not a bounce from a surface. So the torch shows light is more than brightness. It travels, and materials can change its path. The room becomes visible because light from the torch reaches your eyes directly or after bouncing off an object.