Things You'll Need
2 plastic soda bottles (with caps)
1/4 inch drill bit
Washer with 3/8 inch hole
A tornado in a bottle is a great way to teach kids about elemental forces. With a few inexpensive objects, you can replicate a powerful force of nature; after all, a tornado is really nothing more than a spinning column of air (although the top touches the clouds and the bottom touches the ground, which creates all the problems). All you need are two soda bottles and a little device called a tornado tube connector. This can be purchased in a teacher store or from a specialty catalog, but it's also simple to make.
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Remove the caps from the plastic bottles.
Use a strong adhesive (Crazy Glue, for example) to glue the caps together, top to top.
After the caps have dried, drill a 1/4 inch hole through both of them. This is your tornado tube connector!
Fill one soda bottle about 2/3 full of water. Add food coloring for effect, if desired.
Screw one side of the tornado tube connector into the bottle with the water, and the other side into an empty bottle.
Fill one soda bottle about two-thirds full of water.
Place the washer on top of the soda bottle.
Put the empty soda bottle on top of the washer. You might want a second person to hold it stationary.
Bind the bottles together with electrical tape.
Shake the bottle gently to make sure there are no leaks.
The washer method works well and is a bit easier to do (especially for those uncomfortable using drills), but if you're looking for a permanent tornado tube, stick with the first method.
If the tornado tube is used frequently, the electrical tape may need to be replaced every so often.