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Archive for July, 2010

Each of the kids made a prediction about what would happen when we put one straw in the cup, one straw out of the cup and then tried to suck the water up through the straw. Would the water come up through the straw faster, make bubbles, go up one and down the other, or do nothing at all?

Each of the kids took turns and had a very hard time getting any water to travel up the straw, but they were determined to try!
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The Nutshell Reason…

Air moves from areas of higher pressure to areas of lower pressure. When you suck on a straw in a glass of water, the air pressure in your mouth decreases and the water is forced up through the straw {from an area of higher pressure to the lower pressure}.

With two straws, one not being inside the glass, air travels up the second straw into your mouth and the pressure inside your mouth is about equal to the pressure outside…and the water won’t travel up the straw.

After the Experiment…

We had to keep trying! The kids all took turns trying to get the water up the straw. Many giggles and much fun from something super simple!