Beakman explains how refractions works then he turns off the lights to show that we see light bouncing off of objects. He explains that the light bends when it goes into water so this is why a straw looks bent. He then takes a coin and puts it in a dish and fills it with water. The coin can be seen without having to look into the top of the dish. This is how lenses work.
Riley finds the next clue, and the group tries to decipher it. They come to the conclusion that it refers to a specific time. Ben remembers that the back of a one hundred dollar bill has a clocktower, and he uses a bottle of water as a magnifying glass to read the time drawn on the bill.