We can easily observe light with our eyes, and so it is one of the most familiar parts of the world around us. And yet, light often does amazing and unexpected things. Light travels in straight lines from the source to our eyes. This fact allows us to understand many of the cool things that light can do. In this lesson, we will observe how light creates mirages and shadows. And we will build a pinhole camera which makes things appear upside-down. We can understand the upside-down images by thinking about the straight line that the light took from the object to the screen.