Science Sunday: The Fountain Bath

During my Monday Fun
"Magic Science" class this past week,
we did a fun experiment that illustrated the
principle of air pressure
in a fun
(and funny)


The experiment we performed involves
setting up a 2-liter bottle... look like this.

All it takes is some water, a straw,
and a lump of clay...

(You can get more detailed directions for this
entire experiment by clicking HERE
for the Magic Science Journal page.)
I chose one of my kiddos to blow,
as hard as he could,
into the bottle through the straw
until the bottle felt "full."

...he practically jumped out of the way,
so he did not get caught in the resulting
"Fountain Bath!"

The science behind this "magic"
can be explained as follows:

Air is made up of tiny things you can't see called air molecules.

What causes air pressure is the air molecule
whacking into things. If you increase the number of
air molecules somewhere, you'll have more molecules
to whack into things, and the air pressure will increase.
If you decrease the number of air molecules,
the air pressure should go down because
there are fewer molecules to whack into things.

By blowing air into the bottle,
you increase the number of air molecules
in the bottle. That, of course,
increases the air pressure on the inside of the bottle.
When you remove your mouth,
the higher air pressure inside the bottle
pushes the water out towards the lower
air pressure outside.


I let a couple more kiddos try the experiment,
and I was really concerned for...
...this sweet boy, because he blew
until he looked like he was going
to pass out!

(He DID NOT, thankfully...)


For more spectacular science ideas,
check out
Science Sunday...


  1. My Juiciness (makes a mess) does this experiment with his juice boxes-or at least I guess I should look at it this way.

    This is a great and simple experiment for kids. I'm glad he didn't pass out either, but I guess it's nice to know he was really interested in the experiment.

  2. Oh, what a HANDSOME young man you chose! He told me all about this particular experiment!

  3. I'll have to remember this one for a summer time - outdoor activitiy.

  4. That looks like a lot of fun! We'll have to try it.

  5. Fun! My boys are always playing practical jokes on me- I am thinking I might have some fun with this experiment.

  6. Oh that is a good idea, it'd be a great summertime outdoor activity.