How does this format help you visualize the procedure?

1. Tape the washer to the top of either bottle, as shown. (Make sure the tape doesn't cover the hole in the washer.)
2. Fill that bottle three-fourths full of water.
3. Place the empty bottle upside down on top of the washer. Tape the bottles securely together.
4. Turn the bottles over so the one on top holds the water. Quickly swirl the bottles in a big circle several times and place the bottom bottle on a flat surface.
5. When you stop, the water should start swirling down in a tornado-shaped funnel.