Make a fist and put it in the center, the dots go faster! If you twist your fist, they go EVEN FASTER. And if you cover the outer edges, it goes slower. Dude, I’ve been sitting here playing with this and laughing like an idiot for like ten minutes.
One of my favorite things that was shown to me during my elementary age years was an optical illusion. It was the very famous Rubin Vase (pictured below) which you can see in either two ways - as a vase or as two faces that are facing each other.
Iceland Has 3D Zebra Stripe Crosswalk with Stunning Optical Illusion