Knowing that light must be present in order for us to see, first graders are using this knowledge to help design a technology involving light. One of the most useful technologies that uses reflecting light is a periscope. Periscopes allow people to see above and below surfaces without having to physically be in that location.
For example, a scuba diver can see above the ocean's water. Or a pirate can see below the surface! First graders built the periscopes, and changed the way the mirrors tilted to be able to see in a direction their eyes weren't looking! How cool!