1. Heat the nail, while holding it with the pliers, and place a 1/4 inch hole in ONE of the bottles.
2. The hole should be located where your thumb would naturally be placed as you grip the bottle with one hand. In other words, the hole will end up being under your thumb when holding this one bottle.
3. Place large balloons over the top of both bottles, the the balloon inside the empty bottle.
4. Place a pencil in the expanded balloon and "like magic" make the pencil raise out of the bottle.

What occurred as both balloons were attempted to be blown up inside the bottles?
What possible explanations come to mind?
What can you observe about each bottle?
Where might you find this concept at work in nature of in human use?