Tea Leaves

A transparent bowl, partially filled with water containing bits of confetti, is spun for 10 seconds. The water becomes deeper near the outside edge than at the center. When the bowl is quickly stopped, the confetti gradually collect in a pile at the center. Stopping the bowl doesn't stop the water immediately, but it does slow the water moving along the sides and bottom of the bowl. As the water at the bottom of the bowl slows down, it is pushed inward by the the deeper water near the bowl's outer edge. The inward moving water pulls the confetti along with it. This is similar to seeing tea leaves collect in the bottom of a cup after it is stirred.