This is a fun science experiment. There are several variations of this available on the internet and at toy and science stores at your local mall. I like this version because it is inexpensive and the kids get to make it from scratch.
Two 2-liter plastic soda bottles*
Food coloring of your choice
3 x 5-inch index card or piece of thin cardboard
Duct or electrical tape
1. Wash out the soda bottles and remove their labels.
2. Fill one bottle with water and add a teaspoon of the food coloring and a few pinches of glitter.
3. The food coloring color doesn’t really matter, it and the glitter are used to make the cyclone more visible.
4. Roll the index card width-wise so that it will fit in the mouths of the soda bottles.
5. Use masking tape to hold the end of the card in place.
6. Put the rolled-up card in the mouth of the bottle that contains the water.
7. Take the other soda bottle and place its mouth over the rolled-up card, pushing the bottle down so the mouths of both bottles are flush.
8. Tape the mouths of the bottles together with duct or electric tape, making sure that the seal between the two is as waterproof as possible.
9. Grab the bottles by their bases and turn the “cyclone” upside down.
10. As the water begins to pour from one bottle to the other, gently swing the bottles in a counterclockwise motion until the tornado forms.
*Note: You can use small plastic soda bottles, but they don’t give quite the effect desired. I don’t recommend using the 3-liter bottles because they become quite heavy when the water is put in them.