Try this

Do you want to try a fun experiment? It’s very simple.

All you need is a cup full of water, scissors or a knife, a tape measure; and get two straws, one that is taller than the cup by a half of an inch. You always have to cut a straw. It does not matter if the other one is taller or not.
Squat down so your eyes are level with the water in the cup. And hold the straw that’s in the water next to the edge of the cup closest to you. Then blow hard! It does not always work the first time.
A thin stream of water should come out of the straw in the water! What makes it happen? When you blow into the little straw, the water in the straw you are blowing over is forced out of the straw because of air pressure.

Momma says I have to write a warning:

Warning: Get a cloth ready at all times, because this is a very wet experiment!

After you are done, clean up, clean up! Or you’ll get a messy house!