Big Idea:
Light travels in straight lines, which is how shadows form. When light travels through something, it slows down (like if you run into water, you will slow down). When light hits a transparent surface at an angle, it slows and changes direction, or bends. Different materials cause light to refract differently.
The demonstration shows how straight lines from the ray box refract as they hit a surface at an angle, causing them to refract.
What connections can you make to how a magnifying lens works or any other transparent surface that light travels through?