Learning about Air Pressure with a SUPER Long Drinking Straw

On Wednesday I shared a simple activity that only took two supplies. This little experiment is also light on the supplies, but heavy on the learning. 

I taught my boys about air pressure this week using drinking straws.

What You Need
Plastic drinking straws
Tape
Cup filled with beverage of choice

What to Do
My son took a drink of his milk using a straw and I asked him if it was hard to get the liquid up through the straw into his mouth.

"No. Why would it be?"

And so our experiment began. We took about 5 (or maybe six) plastic drinking straws and connected them together.

To do this, use scissors to cut a half inch slit in the end of a straw. Squeeze it slightly to narrow its neck, slip the end of another drinking straw over it. Push it together until there are no wrinkles in the straw. 

Use tape to seal the connection in the straws to ensure it's air tight.

Continue until you have a ridiculously long drinking straw.

Now place your cup on the floor. If your straw is too long to drink standing up above the cup, use a chair (but BE CAREFUL!). Try to hold the straw straight up.

Suck through the straw and try to drink your beverage. Easy or tough? Quick or slow? Little effort or LOTS of effort?

Vary the number of straws and see whether it's easier or harder. Experiment with the angle of the straw.

The Science
When you suck on a straw, air is removed. This difference is air pressure brings the liquid level inside the straw up, eventually moving it all the way up to your mouth so you can swallow a swig.

You've got to have some serious lung power to remove enough air from the straw to make the beverage rise through four straws, though.  

This experiment came from Science Buddies, on Scientific American's website. Stop there for further extensions of this activity and more explanation of the science behind it.