Swirl and Twirl

Swirl and Twirl
Grade Level: 2
Specific Expectation:
2.2 investigate, through experimentation, the characteristics of air (e.g., air takes up space,
has mass) and its uses.
2.3 investigate, through experimentation, the characteristics of water (e.g., water takes up
space, flows or moves when not contained, has mass) and its uses.
Materials Needed:
 2 plastic pop bottles that are the same size.
 Wide Tape.
 Water.
 Food colouring.
1. Fill one of the bottles about 2/3 full with water.
2. Turn the second bottle over and place the opening on the opening of the other bottle
with the water. Tape the two bottles together very securely. Check the seal between
the two bottles for any leaks. Without creating a vortex, ask students what do they
see or hear as the water pours out.
3. To create a model tornado of water, invert the bottles and swirl the top bottle
containing the water in a circular motion. After swirling for a couple of seconds, stop
and watch the water flow into the lower bottle. Ask: What do you think will happen
to the flow of this water?
4. The shape you see should look kind of like a long twirling funnel. This is called a
vortex. Try swirling the top bottle with the water in a larger or smaller circular
pattern. Try swirling it faster or more slowly. Does this affect the shape of your model
tornado? Try larger or smaller plastic bottles and different amounts of water. See if
you can discover a combination that makes the best model tornado.
Scientific Principle:
Why does a Vortex cause the water to pour faster in a plastic bottle? Twirling and swirling
the bottle creates a vortex as the water moves down through the hole in the washer. When the
vortex is generated, air from the bottom bottle can more easily move to the top bottle and the
water comes out quicker. It takes more time for the water to move down when you let the
bottle sit without making a vortex because the water and air must take turns moving through
the hole in a burping effect.
Opportunities and Other Considerations:
Twist of Color - Try adding 2 ounces of colored lamp oil to the water. Lamp oil is available
at most department stores were oil lamps are sold. The oil will float on the surface of the
water since oil is less dense than water. When the oil and water swirl together, the less dense
oil travels down the vortex first and creates a "colored tornado" effect.
Prepared by: Lauren Wakabayashi & Cynthia Peters