The crossover acts like two wires crossing over each other, but not touching each other. Electricity can move along each of the wires, but the crossing paths don’t interfere with each other. It would be impossible to create complicated circuits without wires that cross. Because the crossover allows the paths of the marbles to cross over each other without interfering with the path of the next marble, they are performing one small component of what happens in a circuit board.
"I try to make sure that I create situations that have a little bit of intrigue, a lot of room to fail and [an understanding that] that’s what we expect to do! We expect it not to work the very first time. We expect it to be puzzling. We don’t expect to know it like a google answer. Because that’s where the mystery and the intrigue is--and that’s really where the skill of STEM and science comes in."